Systems, devices, and methods for joint fusion

ABSTRACT

The present invention relates generally to implants and tools for the fixation or fusion of joints or bone segments. These tools include tissue dilators and protectors. Other tools include broaches used to shape bores in bone. The tools can also include a system for removing an implant from bone. Implants can include assemblies of one or more implant structures that make possible the achievement of diverse interventions involving the fusion and/or stabilization of lumbar and sacral vertebra in a non-invasive manner, with minimal incision, and without the necessitating the removing the intervertebral disc. Implants for fusing both sacroiliac joints of a patient include a long implant that extends across both sacroiliac joints.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/805,165, filed Jun. 2, 2022, titled “SYSTEMS, DEVICES, AND METHODSFOR JOINT FUSION” which is a continuation of U.S. patent applicationSer. No. 16/523,992, filed Jul. 26, 2019, now U.S. Pat. No. 11,471,286,titled “SYSTEMS, DEVICES, AND METHODS FOR JOINT FUSION” which is adivisional of U.S. patent application Ser. No. 15/208,588, filed Jul.12, 2016, now U.S. Pat. No. 10,363,140, titled “SYSTEMS, DEVICE, ANDMETHODS FOR JOINT FUSION,” which is a continuation-in-part of U.S.patent application Ser. No. 13/794,542, filed Mar. 11, 2013, titled“TISSUE DILATOR AND PROTECTOR,” now abandoned, which claims priority toU.S. Provisional Application No. 61/609,043, filed Mar. 9, 2012, titled“TISSUE DILATOR AND PROTECTOR,” which are hereby incorporated byreference in its entirety for all purposes.

Said application Ser. No. 15/208,588 is also a continuation-in-part ofU.S. patent application Ser. No. 14/216,790, filed Mar. 17, 2014, titled“SYSTEMS AND METHODS FOR IMPLANTING BONE GRAFT AND IMPLANT,” nowabandoned, which claims priority to U.S. Provisional Application No.61/793,357, filed Mar. 15, 2013, and titled “SYSTEMS AND METHODS FORIMPLANTING BONE GRAFT AND IMPLANT,” which are hereby incorporated byreference in its entirety for all purposes.

Said application Ser. No. 15/208,588 is also a continuation-in-part ofU.S. patent application Ser. No. 14/216,938, filed Mar. 17, 2014, titled“IMPLANTS FOR FACET FUSION,” now abandoned, which claims priority toU.S. Provisional Application No. 61/793,576 filed Mar. 15, 2013, andtitled “IMPLANTS FOR FACET FUSION,” which are hereby incorporated byreference in its entirety for all purposes.

Said application Ser. No. 15/208,588 is also a continuation-in-part ofU.S. patent application Ser. No. 14/217,008, filed Mar. 17, 2014, titled“SYSTEMS AND METHODS FOR REMOVING AN IMPLANT,” now abandoned, whichclaims priority to U.S. Provisional Application No. 61/800,966 filedMar. 15, 2013, and titled “SYSTEMS AND METHODS FOR REMOVING AN IMPLANT,”which are hereby incorporated by reference in its entirety for allpurposes.

Said application Ser. No. 15/208,588 is also a continuation-in-part ofU.S. patent application Ser. No. 14/217,089, filed Mar. 17, 2014, titled“LONG IMPLANT FOR SACROILIAC JOINT FUSION”, now abandoned, which claimspriority to U.S. Patent Application No. 61/798,267 filed Mar. 15, 2013,and titled “LONG IMPLANT FOR SACROILIAC JOINT FUSION,” which are herebyincorporated by reference in its entirety for all purposes.

Said application Ser. No. 15/208,588 is related to U.S. ApplicationPublication No. 2011/0125268 titled “APPARATUS, SYSTEMS, AND METHODS FORACHIEVING LUMBAR FACET FUSION,” which is hereby incorporated byreference in its entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference. For example,this application incorporates by reference in their entireties U.S.Patent Publication No. 2011/0087294 and U.S. Patent Publication No.2011/0118785.

FIELD

This application relates generally to implants and tools for thefixation or fusion of joints or bone segments.

BACKGROUND

Many types of hardware are available both for the fixation of bones thatare fractured and for the fixation of bones that are to be fused(arthrodesed).

For example, the human hip girdle is made up of three large bones joinedby two relatively immobile joints. One of the bones is called the sacrumand it lies at the bottom of the lumbar spine, where it connects withthe L5 vertebra. The other two bones are commonly called “hip bones” andare technically referred to as the right ilium and the left ilium. Thesacrum connects with both hip bones at the sacroiliac joint (inshorthand, the SI-Joint).

The SI-Joint functions in the transmission of forces from the spine tothe lower extremities, and vice-versa. The SI-Joint has been describedas a pain generator for up to 22% of lower back pain.

To relieve pain generated from the SI Joint, sacroiliac joint fusion istypically indicated as surgical treatment, e.g., for degenerativesacroiliitis, inflammatory sacroiliitis, iatrogenic instability of thesacroiliac joint, osteitis condensans ilii, or traumatic fracturedislocation of the pelvis. Currently, screws and screws with plates areused for sacro-iliac fusion. At the same time the cartilage is removedfrom the “synovial joint” portion of the SI joint. This requires a largeincision to approach the damaged, subluxed, dislocated, fractured, ordegenerative joint.

Tissue Dilator and Protector

To reduce soft tissue damage, a tissue dilator can be used to provideaccess to the surgical site. One common type of tissue dilator systemincludes a plurality of tubular sleeves of increasing diameter that aredesigned to slide over a guide pin or guide wire. As dilators ofincreasing diameters are sequentially slid over the guide pin, thetissue surrounding the guide pin is gradually pushed away from the guidepin, resulting in an opening in the tissue.

Systems and Methods for Implanting Bone Graft and Implant

An alternative implant that is not based on the screw design can also beused to fuse the SI-Joint. Such an implant can have a triangularcross-section, for example, as further described below. To insert theimplant, a cavity can be formed into the bone, and the implant can thenbe inserted into the cavity using a tool such as an impactor.

To improve integration of the implant with the bone, bone graft materialcan be applied to the implant before insertion into the bore or duringthe implantation procedure. Therefore, it would be desirable to providesystems, devices and methods for incorporating bone graft materials withthe implant at the implantation site.

In addition, some methods of implantation of the implant require one ormore drilling steps to form the bone cavity for receiving the implant.To reduce the number of drilling steps and simplify the procedure, itwould be desirable to provide a modified broach that can efficiently cutthe bone cavity with less drilling.

Implants for Facet Fusion

The spine (see FIG. 27 ) is a complex interconnecting network of nerves,joints, muscles, tendons and ligaments, and all are capable of producingpain.

The spine is made up of small bones, called vertebrae. The vertebraeprotect and support the spinal cord. They also bear the majority of theweight put upon the spine.

Between each vertebra is a soft, gel-like “cushion,” called anintervertebral disc. These flat, round cushions act like shock absorbersby helping absorb pressure and keep the bones from rubbing against eachother. The intervertebral disc also binds adjacent vertebrae together.The intervertebral discs are a type of joint in the spine.Intervertebral disc joints can bend and rotate a bit but do not slide asdo most body joints.

Each vertebra has two other sets of joints, called facet joints (seeFIG. 28 ). The facet joints are located at the back of the spine(posterior). There is one facet joint on each lateral side (right andleft). One pair of facet joints faces upward (called the superiorarticular facet) and the other pair of facet joints faces downward(called the inferior articular facet). The inferior and superior facetjoints mate, allowing motion (articulation), and link vertebraetogether. Facet joints are positioned at each level to provide theneeded limits to motion, especially to rotation and to prevent forwardslipping (spondylolisthesis) of that vertebra over the one below.

In this way, the spine accommodates the rhythmic motions required byhumans to walk, run, swim, and perform other regular movements. Theintervertebral discs and facet joints stabilize the segments of thespine while preserving the flexibility needed to turn, look around, andget around.

Degenerative changes in the spine can adversely affect the ability ofeach spinal segment to bear weight, accommodate movement, and providesupport. When one segment deteriorates to the point of instability, itcan lead to localized pain and difficulties. Segmental instabilityallows too much movement between two vertebrae. The excess movement ofthe vertebrae can cause pinching or irritation of nerve roots. It canalso cause too much pressure on the facet joints, leading toinflammation. It can cause muscle spasms as the paraspinal muscles tryto stop the spinal segment from moving too much. The instabilityeventually results in faster degeneration in this area of the spine.Degenerative changes in the spine can also lead to spondylolysis andspondylolisthesis. Spondylolisthesis is the term used to describe whenone vertebra slips forward on the one below it. This usually occursbecause there is a spondylolysis (defect) in the vertebra on top. Forexample, a fracture or a degenerative defect in the interarticular partsof lumbar vertebra L1 may cause a forward displacement of the lumbarvertebra L5 relative to the sacral vertebra S1 (called L5-S1pondylolisthesis). When a spondylolisthesis occurs, the facet joint canno longer hold the vertebra back. The intervertebral disc may slowlystretch under the increased stress and allow other upper vertebra toslide forward.

An untreated persistent, episodic, severely disabling back pain problemcan easily ruin the active life of a patient. In many instances, painmedication, splints, or other normally-indicated treatments can be usedto relieve intractable pain in a joint. However, in for severe andpersistent problems that cannot be managed by these treatment options,degenerative changes in the spine may require a bone fusion surgery tostop both the associated disc and facet joint problems.

A fusion is an operation where two bones, usually separated by a joint,are allowed to grow together into one bone. The medical term for thistype of fusion procedure is arthrodesis.

Lumbar fusion procedures have been used in the treatment of pain and theeffects of degenerative changes in the lower back. A lumbar fusion is afusion in the S1-L5-L4 region in the spine.

One conventional way of achieving a lumbar fusion is a procedure calledanterior lumbar interbody fusion (ALIF). In this procedure, the surgeonworks on the spine from the front (anterior) and removes a spinal discin the lower (lumbar) spine. The surgeon inserts a bone graft into thespace between the two vertebrae where the disc was removed (theinterbody space). The goal of the procedure is to stimulate thevertebrae to grow together into one solid bone (known as fusion). Fusioncreates a rigid and immovable column of bone in the problem section ofthe spine. This type of procedure is used to try and reduce back painand other symptoms.

Facet joint fixation procedures have also been used for the treatment ofpain and the effects of degenerative changes in the lower back. Theseprocedures take into account that the facet joint is the only truearticulation in the lumbosacral spine. In one conventional procedure forachieving facet joint fixation, the surgeon works on the spine from theback (posterior). The surgeon passes screws from the spinous processthrough the lamina and across the mid-point of one or more facet joints.

Conventional treatment of spondylolisthesis may include a laminectomy toprovide decompression and create more room for the exiting nerve roots.This can be combined with fusion using, e.g., an autologous fibulargraft, which may be performed either with or without fixation screws tohold the bone together. In some cases the vertebrae are moved back tothe normal position prior to performing the fusion, and in others thevertebrae are fused where they are after the slip, due to the increasedrisk of injury to the nerve with moving the vertebra back to the normalposition.

Currently, these procedures entail invasive open surgical techniques(anterior and/or posterior). Further, ALIF entails the surgical removalof the disc. Like all invasive open surgical procedures, such operationson the spine risk infections and require hospitalization. Invasive opensurgical techniques involving the spine continue to be a challenging anddifficult area.

Systems and Methods for Removing an Implant

An alternative implant that is not based on the screw design can also beused to fuse the SI-Joint and/or the spine. Such an implant can have atriangular cross-section, for example, as further described below. Toinsert the implant, a cavity can be formed into the bone, and theimplant can then be inserted into the cavity using a tool such as animpactor. The implants can then be stabilized together, if desired, byconnected with implants with a crossbar or other connecting device.

Therefore, it would be desirable to provide systems, devices and methodsfor SI-Joint and/or spinal fixation and/or fusion.

Long Implant for Sacroiliac Joint Fusion

An alternative implant that is not based on the screw design can also beused to fuse the SI-Joint and/or the spine. Such an implant can have atriangular cross-section, for example, as further described below. Toinsert the implant, a cavity can be formed into the bone, and theimplant can then be inserted into the cavity using a tool such as animpactor. The implants can then be stabilized together, if desired, byconnected with implants with a crossbar or other connecting device.

Therefore, it would be desirable to provide systems, devices and methodsfor SI-Joint and/or spinal fixation and/or fusion.

SUMMARY OF THE DISCLOSURE

Tissue Dilator and Protector

Some embodiments of the present invention relate generally to tissuedilators and protectors. More specifically, some embodiments relate totissue dilators and protectors used in medical procedures such as bonefixation or fusion.

In some embodiments, a soft tissue protector system for coating animplant with a biologic aid is provided. The system includes alongitudinal body having a distal end, a proximal end and a wall with aninner surface that defines a passage extending through the longitudinalbody, wherein the passage is configured to receive the implant; at leastone port located on the inner surface of the wall proximal the distalend of the longitudinal body; and at least one channel in fluidcommunication with the at least one port, wherein the at least onechannel is configured to contain the biologic aid.

In some embodiments, the system further includes a pusher, wherein thepusher is configured to be inserted into both the passage and the atleast one channel such that the pusher is capable of pushing out theimplant from within the passage and pushing out the biologic aid from atleast one channel through the at least one port to coat the implant asthe implant is pushed out of the passage.

In some embodiments, the inner surface defines a passage having arectilinear transverse cross-sectional profile that is configured toreceive an implant having a corresponding rectilinear transversecross-sectional profile. In some embodiments, the passage and theimplant each have a transverse triangular cross-sectional profile.

In some embodiments, the inner surface comprises a plurality of planarsurfaces, each planar surface defining one side of the rectilinearcross-sectional profile of the passage, wherein each of the plurality ofplanar surfaces comprises at least one port located proximal to thedistal end of the longitudinal body and configured to deliver thebiologic aid.

In some embodiments, the port is a slot oriented transversely to thelongitudinal body.

In some embodiments, the channel is pre-loaded with the biologic aid. Insome embodiments, the biologic aid is selected from the group consistingof bone morphogenetic proteins, hydroxyapatite, demineralized bone,morselized autograft bone, morselized allograft bone, analgesics,antibiotics, and steroids. In some embodiments, the biologic aid isincorporated into a controlled release formulation to provide sustainedrelease of the biologic aid over time.

In some embodiments, an expandable dilator for dilating soft tissue isprovided. The expandable dilator includes a longitudinal body having adistal end, a proximal end and a wall with an inner surface that definesa passage extending through the longitudinal body; wherein the wallcomprises a plurality of longitudinal wall segments, each longitudinalwall segment slidably connected to two other longitudinal wall segments;wherein the longitudinal body has a compressed configuration with afirst transverse cross-sectional area and an expanded configuration witha second transverse cross-sectional area, wherein the first transversecross-sectional area is less than the second transverse cross sectionalarea.

In some embodiments, the longitudinal wall segments have a greateramount of overlap between adjacent longitudinal wall segments in thecompressed configuration than in the expanded configuration.

In some embodiments, the first transverse cross-sectional area and thesecond transverse cross-sectional area are rectilinear.

In some embodiments, the transverse first cross-sectional area and thesecond transverse cross-sectional area are triangular.

In some embodiments, the first transverse cross-sectional area and thesecond transverse cross-sectional area are curvilinear.

In some embodiments, a delivery sleeve for delivering an implant to adelivery site is provided. The delivery sleeve includes a longitudinalbody having a distal end, a proximal end and a wall with an innersurface that defines a passage extending through the longitudinal body,the passage configured to receive the implant; wherein the longitudinalbody includes a flexible tapered distal portion having a plurality oflongitudinal slits that divide the tapered distal portion into at leasttwo expandable blade portions, the expandable blade portions configuredto rotate outwards upon the application of force on the inner surface ofthe expandable blade portions.

In some embodiments, the delivery sleeve further includes an inner tubethat is slidably disposed within the passage of the longitudinal body,wherein the inner tube is configured to apply force on the inner surfaceof the expandable blade portions.

In some embodiments, each longitudinal slit terminates at a stressrelief cutout.

In some embodiments, the longitudinal body has a rectilinear transversecross-section.

In some embodiments, the longitudinal body has a triangular transversecross-section.

In some embodiments, the delivery sleeve further includes an adjustingsleeve that is controllably disposed within the passage of thelongitudinal body to extend the length of the passage.

In some embodiments, a dilator system is provided. The system includes aguide pin configured to be inserted within bone, the guide pin having adistal portion comprising a plurality of outwardly biased prongs; aretractable cannula disposed around the outwardly biased prongs to keepthe outwardly biased prongs in a collapsed configuration; one or moredilators that are configured to be sequentially disposed over the guidepin; and an outer cannula configured to be disposed over the one or moreof dilators, the outer cannula having a plurality of stabilizing pinsdisposed around the circumference of the outer cannula, wherein thestabilizing pins are configured to be inserted within bone.

In some embodiments, the one or more dilators includes a drill dilatorand a broach dilator.

In some embodiments, the broach dilator has a rectilinear transversecross-section and the outer cannula has a rectilinear transversecross-section.

In some embodiments, the plurality of stabilizing pins are slidablydisposed within channels located around the circumference of the outercannula.

In some embodiments, the one or more dilators and outer cannula areradiolucent and the guide pin and the stabilizing pins are radiopaque.

In some embodiments, a quick connect system is provided. The systemincludes a dilator having a proximal end and a distal end, the proximalend of the dilator having a first quick connect feature; and a handlehaving a proximal end and a distal end, the distal end of the handlehaving a second quick connect feature, wherein the first quick connectfeature is configured to reversibly connect with the second quickconnect feature.

In some embodiments, the first quick connect feature is an L or J shapedslot and the second quick connect feature is a pin, wherein the L or Jshaped slot is configured to receive the pin.

In some embodiments, the first quick connect feature comprises a grooveand at least one pin or bearing receptacle and the second quick connectfeature comprises a collar with at least one spring loaded pin orbearing.

In some embodiments, a method of inserting an implant into a bone cavityis provided. The method includes providing an implant loaded into alumen of a dilator having a proximal end and a distal end, the lumen ofthe dilator defined by a wall having an interior surface with one ormore ports located proximal to distal end of the dilator, the one ormore ports in communication with one or more channels within the wall,the one or more channels containing a biologic aid; positioning thedistal end of the dilator adjacent to the bone cavity; advancing apusher simultaneously through the lumen of the dilator and the one ormore channels to simultaneously advance the implant into the bone cavityand eject the biologic aid out of the one or more ports, thereby coatingthe implant with the biologic aid as the implant is advanced into thebone cavity.

In some embodiments, a method of inserting an implant into a bone cavityis provided. The method includes providing an implant loaded into thelumen of a dilator having a proximal end and a distal end, the dilatorincluding a reservoir of biologic aid; positioning the distal end of thedilator adjacent to the bone cavity; and advancing the implant into thebone cavity while simultaneously coating the implant with the biologicaid.

In some embodiments, a method of inserting an implant into bone isprovided. The method includes inserting a guide pin into the bone;disposing an expandable dilator over the guide pin and against the bone;disposing a drill bit over the guide pin; drilling a hole in the bonewith the drill bit to form a channel in the bone; withdrawing the drillbit from the channel; expanding the expandable dilator from a contractedconfiguration to an expanded configuration; disposing a broach over theguide pin and inserting the broach into the channel to enlarge andreshape the channel into a bone cavity; and inserting the implant overthe guide pin and into the bone cavity.

In some embodiments, the bone cavity has a rectilinear transversecross-section.

In some embodiments, the method further includes retracting a sleevefrom a distal portion of the guide pin to deploy a plurality of outwardbiased prongs that form the distal portion or the guide pin.

In some embodiments, the method further includes inserting into the boneone or more stabilizing pins to secure the expandable dilator to thebone.

In some embodiments, the method further includes attaching a handle tothe expandable dilator using a quick connect mechanism.

Systems and Methods for Implanting Bone Graft and Implant

Some embodiments relate generally to broaches. More specifically, someembodiments relate to broaches used to shape bores in bone. The broachescan shape the bores to receive an implant and also cut additional tubesor channels for receiving bone graft material and/or biologic aids.

In general, in one embodiment, a broach for shaping a bore in bone toreceive an implant includes an elongate body with a proximal end, adistal end, at least three faces between the distal end and the proximalend, a plurality of apices formed at the junctions between adjacentfaces, and a longitudinal axis. A lumen extends throughout the elongatebody about the longitudinal axis, and the lumen is sized and shaped forreceiving a guide pin. A plurality of cutting surfaces are located onthe distal end of the elongate body for shaping the bore to receive theimplant, and the plurality of cutting surfaces are oriented along theplurality of apices and become progressively smaller in size towards thedistal end. A plurality of additional cutting surfaces is aligned withthe plurality of apices for cutting channels in the bore to receive abone graft material.

This and other embodiments can include one or more of the followingfeatures. Each face of the elongate body can include a channel extendingalong at least a portion of the longitudinal length of the elongatebody. The elongate body can include three faces that define asubstantially triangular cross-sectional profile transverse to thelongitudinal axis. The plurality of cutting surfaces can be angledtowards the distal end of the elongate body. The plurality of additionalcutting surfaces can be partially circular. The plurality of additionalcutting surfaces can be partially rectilinear.

In general, in one embodiment, a method for inserting an implant in boneincludes: (1) drilling a bore into the bone; (2) inserting a broach toshape the bore to receive the implant and to form channels for receivinga bone graft material; (3) inserting the implant into the shaped bore;and (4) filling the channels with a bone graft material.

This and other embodiments can include one or more of the followingfeatures. The shaped bore can be rectilinear with a plurality of apices,and the channels can be formed at the apices of the shaped bore. Theshaped bore can be triangular. The method can include inserting a guidepin into the bone. The steps of drilling a bore, inserting a broach, andinserting the implant all can be performed over the guide pin.

In general, in one embodiment, a broach for shaping a bore in bone toreceive an implant includes an elongate body with a proximal end, adistal end, at least three faces between the distal end and the proximalend, a plurality of apices formed at the junctions between adjacentfaces, and a longitudinal axis. A lumen extends throughout the elongatebody about the longitudinal axis, and the lumen is sized and shaped forreceiving a guide pin. A plurality of cutting surfaces is located on thedistal end of the elongate body for shaping the bore to receive theimplant. The plurality of cutting surfaces are oriented along theplurality of apices and become progressively smaller in size towards thedistal end. A tapered distal tip portion at the distal end of theelongate body tapers to a distal opening of the lumen.

This and other embodiments can include one or more of the followingfeatures. The tapered distal tip portion can form a cutting surfacearound the opening of the lumen. The tapered distal tip portion caninclude a plurality of beveled faces that are angled towards the distalend. The tapered distal tip portion can include a smooth taperingsurface that reaches the distal opening of the lumen. The elongate bodycan include three faces that define a substantially triangularcross-sectional profile transverse to the longitudinal axis. Theplurality of cutting surfaces can be angled towards the distal end ofthe elongate body. Each face of the elongate body can include a channelextending along at least a portion of the longitudinal length of theelongate body.

In general, in one embodiment, a method for inserting an implant in boneincludes: (1) inserting a guide pin into the bone; (2) inserting a sharptipped broach over the guide pin to create a cavity for receiving theimplant, wherein the cavity can be formed without first drilling a boreinto the bone over the guide pin; and (3) inserting the implant into thecavity.

This and other embodiments can include one or more of the followingfeatures. The step of inserting a sharp tipped broach over the guide pinto create a cavity can include cutting the bone adjacent to the guidepine with one or more cutting edges at a distal end of the sharp tippedbroach, and driving the sharp tipped broach further into the bone untila plurality of cutting surfaces on the sharp tipped broach can cut intoand remove the bone surrounding the guide pin to form the cavity.

Implants for Facet Fusion

Embodiments of the present invention relate to apparatus, systems, andmethods for the fusion and/or stabilization of the lumbar spine. Theapparatus, systems, and methods include one or more elongated, stem-likeimplant structures sized and configured for the fusion or stabilizationof adjacent bone structures in the lumbar region of the spine, eitheracross the intervertebral disc or across one or more facet joints. Eachimplant structure can include a region formed along at least a portionof its length to promote bony in-growth onto or into surface of thestructure and/or bony growth entirely through all or a portion of thestructure. The bony in-growth or through-growth region along the surfaceof the implant structure accelerates bony in-growth or through-growthonto, into, or through the implant structure 20. The implant structuretherefore provides extra-articular/intra osseous fixation, when bonegrows in and around the bony in-growth or through-growth region. Bonyin-growth or through-growth onto, into, or through the implant structurehelps speed up the fusion and/or stabilization process of the adjacentbone regions fixated by the implant structure. The implant structure canalso be curved.

The assemblies of one or more implant structures make possible theachievement of diverse interventions involving the fusion and/orstabilization of lumbar and sacral vertebra in a non-invasive manner,with minimal incision, and without the necessitating the removing theintervertebral disc. The representative lumbar spine interventions,which can be performed on adults or children, include, but are notlimited to, lumbar interbody fusion; translaminar lumbar fusion; lumbarfacet fusion; trans-iliac lumbar fusion; and the stabilization of aspondylolisthesis.

In some embodiments, an implant for fusing a facet joint of a patient isprovided. The implant can include an elongate body having a proximalend, a distal end and a lumen extending between the proximal end and thedistal end, wherein the elongate body has a curvature extending from theproximal end to the distal end and a rectilinear or curvilineartransverse cross-sectional profile.

In some embodiments, the elongate body is sized and configured to fusethe facet joint of the patient.

In some embodiments, the elongate body is formed of a shape memorymaterial having a straight configuration and a curved configuration.

In some embodiments, the elongate body is formed of a plurality ofinterlocking segments.

In some embodiments, the elongate body is inflatable with a curablematerial.

In some embodiments, the elongate body comprises a valve.

In some embodiments, the elongate body is made of an inelastic materialthat cannot stretch.

In some embodiments, the elongate body is made of an elastic materialthat can stretch.

In some embodiments, the curvature is constant.

In some embodiments, the curvature is variable.

In some embodiments, the transverse cross-sectional profile istriangular.

In some embodiments, the transverse cross-sectional profile is circular.

In some embodiments, the elongate body has an exterior surface treatedto promote bony in-growth.

In some embodiments, the exterior surface has a rough texture.

In some embodiments, a method for lumbar facet fusion is provided. Themethod can include creating a curved insertion path that extends from aninferior articular process of a selected lumbar vertebra in a caudaldirection through the adjoining facet capsule into a correspondingsuperior articular process of an adjacent lumbar vertebra and into apedicle of the adjacent lumbar vertebra; providing a curved bonefixation implant comprising a curved elongated implant structure havinga longitudinal axis and a rectilinear cross section transverse to thelongitudinal axis and including an exterior surface region treated toprovide bony in-growth or through-growth along the implant structure;and inserting the curved bone fixation implant through the insertionpath from the inferior articular process of the selected lumbarvertebra, in a caudal direction through the adjoining facet capsule intothe corresponding superior articular process of the adjacent lumbarvertebra and into a pedicle of the adjacent lumbar vertebra.

In some embodiments, a method for translaminal lumbar fusion isprovided. The method can include creating a curved insertion path thatextends from a superior articular process of a selected lumbar vertebra,cranially through the adjoining facet capsule into a correspondinginferior articular process of an adjacent lumbar vertebra, and, fromthere, further through the lamina of the adjacent vertebra into aninterior opposite posterolateral region adjacent the spinous process ofthe adjacent vertebra; providing a curved bone fixation implantcomprising a curved elongated implant structure having a rectilinearcross section including an exterior surface region treated to providebony in-growth or through-growth along the implant structure; andinserting the curved bone fixation implant through the insertion pathfrom the superior articular process of the selected lumbar vertebra,cranially through the adjoining facet capsule into the inferiorarticular process of the adjacent lumbar vertebra, and, from there,further through the lamina of the adjacent vertebra into an interioropposite posterolateral region adjacent the spinous process of theadjacent vertebra.

In some embodiments, the step of creating a curved insertion pathfurther includes inserting a curved guide pin into the superiorarticular process of a selected lumbar vertebra along the curvedinsertion path; and advancing a drill or cutting device over the curvedguidewire along the curved insertion path.

In some embodiments, the step of inserting the curved guide pin includesrotating the curved guide pin about an axis.

In some embodiments, the step of creating a curved insertion pathfurther includes advancing a drill or cutting device along the curvedinsertion path.

In some embodiments, a method for translaminal lumbar fusion of asuperior vertebra to an inferior vertebrae is provided. The method caninclude creating a curved insertion path that starts in the lamina ofthe superior vertebra, extends distally and laterally to the inferiorarticular process of the superior vertebra, through the joint betweenthe superior vertebra and the inferior vertebrae, and into the superiorarticular process of the inferior vertebra; providing a curved bonefixation implant comprising a curved elongated implant structure havinga rectilinear cross section including an exterior surface region treatedto provide bony in-growth or through-growth along the implant structure;and inserting the curved bone fixation implant through the insertionpath from the lamina of the superior vertebra, extending distally andlaterally to the inferior articular process of the superior vertebra,through the joint between the superior vertebra and the inferiorvertebrae, and into the superior articular process of the inferiorvertebra.

Systems and Methods for Removing an Implant

Embodiments of the present invention relate generally to systems andmethods for removing an implant from bone.

In some embodiments, a system for removing an implant from bone, whereinthe implant has a plurality of sides and a rectilinear cross-section, isprovided. The system includes a guidepin; an osteotome having a flat,elongate body with proximal end, a distal end, and a sharp, bladeportion for cutting bone located at the distal end of the elongate body;an osteotome guide having an elongate body having a plurality of planarfaces and a rectilinear cross-section that corresponds in shape to therectilinear cross-section of the implant, a lumen extending through theelongate body of the osteotome for receiving the guidepin, and aplurality of channels for receiving the osteotome, wherein one of theplurality of channels is disposed along each one of the plurality ofplanar faces.

In some embodiments, the guidepin has a distal end comprising a maleconnector for attachment into a corresponding female connector of theimplant.

In some embodiments, the sharp, blade portion of the osteotome has awidth that is equal to the width of one of the sides of the implant.

In some embodiments, the sharp, blade portion of the osteotome has awidth that is greater than the width of one of the sides of the implant.

In some embodiments, the system further includes a dilator having aproximal end and a distal end, wherein the distal end of the dilatorcomprises at least one cutout.

In some embodiments, the system further includes an adjustable stopattached to the osteotome guide for limiting the depth of insertion ofthe osteotome guide within the dilator.

In some embodiments, the system further includes a blank having a flatelongate body with a blade portion for cutting bone located at thedistal end of the elongate body, the blank sized and shaped to bedisposed into the plurality of channels, the blank configured to betapped into the bone to secure the osteotome guide in place.

In some embodiments, the blank comprises a receptacle extending throughthe flat elongate body for receiving a stop, wherein the stop isconfigured to reversibly hold the blank in place with respect to theosteotome.

In some embodiments, the guidepin has a threaded distal end forattachment to corresponding internal threads of the implant.

In some embodiments, the guidepin has a threaded proximal end that canbe reversibly connected to a pull handle or pull shaft.

In some embodiments, a system for removing an implant from bone, whereinthe implant has a plurality of sides and a rectilinear cross-section, isprovided. The system includes a guidepin; an osteotome having a V-shapedelongate body with a proximal end, a distal end, a sharp, V-shaped bladeportion for cutting bone located at the distal end of the elongate body,and a lumen extending through a portion of the elongate body forreceiving the guidepin, wherein the angle of the V-shaped blade portionis the same as the angle between two sides of the implant.

In some embodiments, the V-shaped blade portion comprises a first planarsection having a width equivalent to the width of a first side of theimplant, and a second planar section having a width equivalent to thewidth of a second side of the implant.

In some embodiments, the V-shaped blade portion comprises a first planarsection having a width that is between about half the width to the fullwidth of a first side of the implant, and a second planar section havinga width that is between about half the width to the full width of asecond side of the implant.

In some embodiments, a system for removing an implant from bone, whereinthe implant has a plurality of sides and a rectilinear cross-section, isprovided. The system can include a guidepin; an osteotome having aV-shaped elongate body with a proximal end, a distal end, a sharp, and aV-shaped blade portion for cutting bone located at the distal end of theelongate body, wherein the angle of the V-shaped blade portion is thesame as the angle between two sides of the implant; and an osteotomeguide having an elongate body having a plurality of planar faces and arectilinear cross-section that corresponds in shape to the rectilinearcross-section of the implant, a lumen extending through the elongatebody of the osteotome for receiving the guidepin, and at least onechannel for receiving the osteotome, wherein the at least one channel isV-shaped and is disposed along two adjacent planar faces.

In some embodiments, a method for removing an implant having arectilinear cross-section from a bone matrix is provided. The method caninclude attaching a guidepin to the implant; disposing an osteotomeguide over the guidepin; aligning the osteotome guide with the implant;inserting an osteotome into a channel in the osteotome guide; cuttingthe bone matrix away from the implant with the osteotome; and pulling onthe guidepin to remove the implant from the bone matrix and leave acavity in the bone matrix.

In some embodiments, the method further includes inserting a replacementimplant having a larger cross-sectional profile than the removed implantinto the cavity.

In some embodiments, the method further includes disposing a dilatorover the guidepin, wherein the dilator has a proximal end and a distalend having at least one cutout, and wherein the osteotome guide isinserted within the dilator.

In some embodiments, the method further includes aligning the at leastone cutout of the dilator over a second implant in the bone matrix.

In some embodiments, the method further includes limiting the depth inwhich the osteotome guide is inserted within the dilator by adjusting astop attached to the osteotome guide.

In some embodiments, the method further includes attaching a pull handleto the guidepin.

In some embodiments, the osteotome guide has at least two channels.

In some embodiments, the method further includes inserting a blank intoone of the channels of the osteotome guide; and tapping the blank intothe bone matrix to secure the osteotome guide in place.

In some embodiments, the method further includes securing the blank inplace in the channel of the osteotome guide.

In some embodiments, a method for removing an implant having arectilinear cross-section from a bone matrix is provided. The methodincludes attaching a guidepin to the implant; disposing over theguidepin an osteotome having a V-shaped elongate body with a proximalend, a distal end, a V-shaped blade portion for cutting bone located atthe distal end of the elongate body, and a lumen extending through aportion of the elongate body for receiving the guidepin; aligning theV-shaped blade portion with two adjacent faces of the rectilinearimplant; driving the V-shaped blade portion into the bone matrix to cutaway the bone matrix from two adjacent faces of the rectilinear implant;and pulling on the guidepin to remove the implant from the bone matrixand leave a cavity in the bone matrix.

In some embodiments, the method further includes removing the V-shapedblade portion from the bone matrix; aligning the V-shaped blade portionwith at least one remaining uncut face of the rectilinear implant; anddriving the V-shaped blade portion into the bone matrix to cut away thebone matrix from the at least one remaining uncut face of therectilinear implant.

In some embodiments, a system for removing an implant from bone, whereinthe implant has a plurality of sides and a rectilinear cross-section, isprovided. The system can include an osteotome having a flat, elongatebody with proximal end, a distal end, and a sharp, blade portion forcutting bone located at the distal end of the elongate body; and anosteotome guide having an elongate body having a plurality of planarfaces and a rectilinear cross-section that corresponds in shape to therectilinear cross-section of the implant, and a plurality of channelsfor receiving the osteotome, wherein one of the plurality of channels isdisposed along each one of the plurality of planar faces.

In some embodiments, a device for removing an implant from bone, whereinthe implant has a plurality of sides and a rectilinear cross-section, isprovided. The system can include an elongate body with a proximal end, adistal end, a sharp, V-shaped blade portion for cutting bone located atthe distal end of the elongate body, wherein the angle of the V-shapedblade portion is the same as the angle between two sides of the implant.

Long Implant for Sacroiliac Joint Fusion

Embodiments of the present invention relate generally to an implant forSI-Joint fusion.

In some embodiments, a system for the fusion of the sacroiliac joint isprovided. The system includes a guide pin having a length greater thanthe width of a patient's pelvis, the guide pin having a proximal endwith a first alignment feature and a distal end with a second alignmentfeature; a broach having a lumen for receiving the guide pin, the lumenhaving a complementary alignment feature that is configured to interactwith the first alignment feature and the second alignment feature toregister the broach with the guide pin in a predetermined orientation,the broach configured to form a rectilinear cavity in bone; and animplant having a rectilinear cross-section transverse to a longitudinalaxis of the implant, the implant having a length greater than the widthbetween a surface of the patient's right ilium and a surface of thepatient's left ilium, the implant sized to fit through a cavity formedby the broach.

In some embodiments, the implant has a rough surface.

In some embodiments, the implant has a triangular cross-sectiontransverse to the longitudinal axis of the implant.

In some embodiments, the implant has a rectangular or squarecross-section transverse to the longitudinal axis of the implant.

In some embodiments, the first alignment feature and the secondalignment feature are selected from the group consisting of lines,ridges, slots, and pins.

In some embodiments, a system for the fusion of the sacroiliac joint isprovided. The system can include a guide pin having a length greaterthan the width of a patient's pelvis; a broach having a lumen forreceiving the guide pin, the broach configured to form a rectilinearcavity in bone; and an implant having a rectilinear cross-sectiontransverse to a longitudinal axis of the implant, the implant having alength greater than the width between a surface of the patient's rightilium and a surface of the patient's left ilium, the implant sized tofit through the rectilinear cavity formed by the broach.

In some embodiments, the implant has a length greater than the widthbetween a surface of the patient's right ilium and a surface of thepatient's left ilium by about 2 to 20 mm.

In some embodiments, the implant has a length between about 100 mm to300 mm.

In some embodiments, the guide pin has an alignment feature that extendsacross the length of the guide pin.

In some embodiments, a method for fusing both sacroiliac joints of apatient is provided. The method can include inserting a guide pinthrough the first ilium and across the first SI-Joint, through thesacrum and above the S1 foramen, across the second SI-Joint, and throughthe second ilium; forming a first rectilinear cavity through the firstilium and the first SI-Joint; forming a second rectilinear cavitythrough the second ilium and the second SI-Joint, wherein the firstrectilinear cavity and the second rectilinear cavity are aligned; andinserting an implant through the first cavity, across the firstSI-Joint, through the sacrum, across the second SI-Joint, and throughthe second cavity, wherein the implant has a rectilinear cross-sectiontransverse to a longitudinal axis of the implant that corresponds to thefirst rectilinear cavity and the second rectilinear cavity.

In some embodiments, the step of forming the first rectilinear cavityincludes aligning a broach with an alignment feature on the guide pin.

In some embodiments, the step of forming the second rectilinear cavityincludes aligning the broach with the alignment feature of the guidepin.

In some embodiments, the step of forming the second rectilinear cavityincludes aligning the broach with a second alignment feature on theguide pin.

In some embodiments, the step of forming the second rectilinear cavityincludes aligning a broach with an image of the first rectilinear cavityunder fluoroscopy.

In some embodiments, the method further includes determining a length ofthe guide pin residing between the surface of the first ilium and thesurface of the second ilium; and sizing the implant based on thedetermined length of the guide pin residing between the surface of thefirst ilium and the surface of the second ilium.

In some embodiments, the step of determining the length of the guide pinresiding between the surface of the first ilium and the surface of thesecond ilium includes measuring the length of the guide pin extendingfrom the surface of the first ilium and the surface of the second ilium.

In some embodiments, the implant has a length that is about 2 to 20 mmgreater than the determined length of the guide pin residing between thesurface of the first ilium and the surface of the second ilium.

In some embodiments, the step of forming the first rectilinear cavityincludes drilling a first bore over the guide pin in the first ilium;and shaping the first bore with a broach.

In some embodiments, a method for fusing both sacroiliac joints of apatient is provided. The method includes inserting a guide pin throughthe first ilium and across the first SI-Joint, through the sacrumbetween the S1 and S2 foramen, across the second SI-Joint, and throughthe second ilium; forming a first rectilinear cavity through the firstilium and the first SI-Joint; forming a second rectilinear cavitythrough the second ilium and the second SI-Joint, wherein the firstrectilinear cavity and the second rectilinear cavity are aligned; andinserting an implant through the first cavity, across the firstSI-Joint, through the sacrum, across the second SI-Joint, and throughthe second cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1A is a perspective view of an embodiment of a dilator with anintegrated infusion system.

FIG. 1B is a longitudinal cross-sectional view of the dilator shown inFIG. 1A.

FIGS. 2A-2G illustrate embodiments of an expandable dilator.

FIGS. 3A-3C illustrate additional embodiments of the dilator.

FIGS. 4A and 4B show an embodiment of a delivery sleeve that can be usedin place of a dilator.

FIGS. 5A-5C illustrate an embodiment of a sequential dilation system.

FIGS. 6A-6D illustrate embodiments of a quick change mechanism thatallows two instruments or components to be quickly and reversiblyconnected together.

FIG. 7 illustrates an embodiment of an implant structure.

FIGS. 8A-8D are side section views of the formation of a broached borein bone according to one embodiment of the invention.

FIGS. 8E and 8F illustrate an embodiment of the assembly of a softtissue protector or dilator with a drill sleeve and a guide pin sleeve.

FIGS. 9 and 10 are, respectively, anterior and posterior anatomic viewsof the human hip girdle comprising the sacrum and the hip bones (theright ilium, and the left ilium), the sacrum being connected with bothhip bones at the sacroiliac joint (in shorthand, the SI-Joint).

FIGS. 11, 12, 13A and 13B are anatomic views showing, respectively, apre-implanted perspective, implanted perspective, implanted anteriorview, and implanted cranio-caudal section view, the implantation ofthree implant structures for the fixation of the SI-Joint using alateral approach through the ilium, the SI-Joint, and into the sacrum.

FIG. 14 illustrates an embodiment of an implant structure.

FIGS. 15A-15D are side section views of the formation of a broached borein bone according to one embodiment of the invention.

FIGS. 15E and 15F illustrate the assembly of a soft tissue protectorsystem for placement over a guide wire.

FIGS. 16 and 17 are, respectively, anterior and posterior anatomic viewsof the human hip girdle comprising the sacrum and the hip bones (theright ilium, and the left ilium), the sacrum being connected with bothhip bones at the sacroiliac joint (in shorthand, the SI-Joint).

FIGS. 18, 19, 20A and 20B are anatomic views showing, respectively, apre-implanted perspective, implanted perspective, implanted anteriorview, and implanted cranio-caudal section view, the implantation ofthree implant structures for the fixation of the SI-Joint using alateral approach through the ilium, the SI-Joint, and into the sacrum.

FIGS. 21A-21E illustrate embodiments of a modified broach for removingadditional bone from a bore so that a bone graft or other material canbe added with the implant.

FIGS. 22A and 22B illustrate an embodiment of a standard broach with aflat distal face.

FIGS. 23A and 23B illustrate an embodiment of the broach with a pointeddistal tip portion.

FIGS. 24A and 24B illustrate an embodiment of the broach with anadditional cutting surface located at the distal end of the broach.

FIGS. 25A and 25B illustrate an embodiment of the broach with a pyramidshaped distal tip.

FIG. 26 illustrates a CT scan with haloing artifacts around the implant.

FIG. 27 is an anatomic anterior and lateral view of a human spine.

FIG. 28 is an anatomic posterior perspective view of the lumbar regionof a human spine, showing lumbar vertebrae L2 to L5 and the sacralvertebrae.

FIG. 29 is an anatomic anterior perspective view of the lumbar region ofa human spine, showing lumbar vertebrae L2 to L5 and the sacralvertebrae.

FIG. 30 is a perspective view of a representative embodiment of anelongated, stem-like, cannulated implant structure well suited for thefusion or stabilization of adjacent bone structures in the lumbar regionof the spine, either across the intervertebral disc or across one ormore facet joints.

FIGS. 31, 32, 33 and 34 are perspective views of other representativeembodiments of implant structures well suited for the fusion orstabilization of adjacent bone structures in the lumbar region of thespine, either across the intervertebral disc or across one or more facetjoints.

FIG. 35 is an anatomic anterior perspective view showing, in an explodedview prior to implantation, a representative configuration of anassembly of one or more implant structures as shown in FIG. 30 , sizedand configured to achieve anterior lumbar interbody fusion, in anon-invasive manner and without removal of the intervertebral disc.

FIG. 36 is an anatomic anterior perspective view showing the assemblyshown in FIG. 35 after implantation.

FIG. 37 is an anatomic right lateral perspective view showing theassembly shown in FIG. 35 after implantation.

FIG. 38 is an anatomic superior left lateral perspective view showingthe assembly shown in FIG. 35 after implantation.

FIGS. 39A to 39G are diagrammatic views showing, for purposes ofillustration, a representative lateral (or posterolateral) procedure forimplanting the assembly of implant structures shown in FIGS. 36 to 38 .

FIG. 40 is an anatomic anterior perspective view showing, in an explodedview prior to implantation, assemblies comprising one or more implantstructures like that shown in FIG. 30 inserted from left and/or rightanterolateral regions of a given lumbar vertebra, in an angled paththrough the intervertebral disc and into an opposite anterolateralinterior region of the next inferior lumbar vertebra, FIG. 40 showing inparticular two implant structures entering on the right anterolateralside of L4, through the intervertebral disc and into the leftanterolateral region of L5, and one implant structure entering on theleft anterolateral side of L4, through the intervertebral disc and intothe right anterolateral region of L5, the left and right implantstructures crossing each other in transit through the intervertebraldisc.

FIG. 41 is an anatomic anterior perspective view showing, in an explodedview prior to implantation, assemblies comprising one or more implantstructures like that shown in FIG. 30 inserted from left and/or rightanterolateral regions of a given lumbar vertebra, in an angled paththrough the intervertebral disc and into an opposite anterolateralinterior region of the next inferior lumbar vertebra, FIG. 40 showing inparticular one implant structure entering on the right anterolateralside of L4, through the intervertebral disc and into the leftanterolateral region of L5, and one implant structure entering on theleft anterolateral side of L4, through the intervertebral disc and intothe right anterolateral region of L5, the left and right implantstructures crossing each other in transit through the intervertebraldisc.

FIG. 42 is an anatomic posterior perspective view, exploded prior toimplantation, of a representative configuration of an assembly of one ormore implant structures like that shown in FIG. 30 , sized andconfigured to achieve translaminar lumbar fusion in a non-invasivemanner and without removal of the intervertebral disc.

FIG. 43 is an anatomic inferior transverse plane view showing theassembly shown in FIG. 42 after implantation.

FIG. 44 is an anatomic posterior perspective view, exploded prior toimplantation, of a representative configuration of an assembly of one ormore implant structures like that shown in FIG. 30 , sized andconfigured to achieve lumbar facet fusion, in a non-invasive manner andwithout removal of the intervertebral disc.

FIG. 45 is an anatomic inferior transverse plane view showing theassembly shown in FIG. 44 after implantation.

FIG. 46 is an anatomic lateral view showing the assembly shown in FIG.44 after implantation.

FIG. 47 is an embodiment of a curved implant structure.

FIG. 48 is another embodiment of a curved implant structure formed frominterconnected segments.

FIG. 49 is another embodiment of a curved implant structure that isinflatable.

FIG. 50 is an anatomic posterior perspective view, exploded prior toimplantation, of a representative configuration of an assembly of one ormore implant structures like that shown in FIGS. 47-49 , sized andconfigured to achieve translaminar lumbar fusion in a non-invasivemanner and without removal of the intervertebral disc.

FIG. 51 is an anatomic inferior transverse plane view showing theassembly shown in FIG. 50 after implantation.

FIG. 52 is an anatomic posterior perspective view, exploded prior toimplantation, of a representative configuration of an assembly of one ormore implant structures like that shown in FIGS. 47-49 , sized andconfigured to achieve lumbar facet fusion, in a non-invasive manner andwithout removal of the intervertebral disc.

FIG. 53 is an anatomic inferior transverse plane view showing theassembly shown in FIG. 52 after implantation.

FIG. 54 is an anatomic lateral view showing the assembly shown in FIG.52 after implantation.

FIG. 55 illustrates an embodiment of an implant structure.

FIGS. 56A-56D are side section views of the formation of a broached borein bone according to one embodiment of the invention.

FIGS. 56E and 56F illustrate the assembly of a soft tissue protectorsystem for placement over a guide wire.

FIGS. 57 and 58 are, respectively, anterior and posterior anatomic viewsof the human hip girdle comprising the sacrum and the hip bones (theright ilium, and the left ilium), the sacrum being connected with bothhip bones at the sacroiliac joint (in shorthand, the SI-Joint).

FIGS. 59, 60, 61A and 61B are anatomic views showing, respectively, apre-implanted perspective, implanted perspective, implanted anteriorview, and implanted cranio-caudal section view, the implantation ofthree implant structures for the fixation of the SI-Joint using alateral approach through the ilium, the SI-Joint, and into the sacrum.

FIG. 62A is an anatomic anterior and lateral view of a human spine.

FIG. 62B is an anatomic posterior perspective view of the lumbar regionof a human spine, showing lumbar vertebrae L2 to L5 and the sacralvertebrae.

FIG. 62C is an anatomic anterior perspective view of the lumbar regionof a human spine, showing lumbar vertebrae L2 to L5 and the sacralvertebrae.

FIG. 63 is an anatomic anterior perspective view showing, in an explodedview prior to implantation, a representative configuration of anassembly of one or more implant structures as shown in FIG. 55 , sizedand configured to achieve anterior lumbar interbody fusion, in anon-invasive manner and without removal of the intervertebral disc.

FIG. 64 is an anatomic anterior perspective view showing the assemblyshown in FIG. 63 after implantation.

FIG. 65 is an anatomic right lateral perspective view showing theassembly shown in FIG. 63 after implantation.

FIG. 66 is an anatomic superior left lateral perspective view showingthe assembly shown in FIG. 63 after implantation.

FIGS. 67A to 67G are diagrammatic views showing, for purposes ofillustration, a representative lateral (or posterolateral) procedure forimplanting the assembly of implant structures shown in FIGS. 64 to 66 .

FIG. 68 is an anatomic anterior perspective view showing, in an explodedview prior to implantation, assemblies comprising one or more implantstructures like that shown in FIG. 55 inserted from left and/or rightanterolateral regions of a given lumbar vertebra, in an angled paththrough the intervertebral disc and into an opposite anterolateralinterior region of the next inferior lumbar vertebra, FIG. 68 showing inparticular two implant structures entering on the right anterolateralside of L4, through the intervertebral disc and into the leftanterolateral region of L5, and one implant structure entering on theleft anterolateral side of L4, through the intervertebral disc and intothe right anterolateral region of L5, the left and right implantstructures crossing each other in transit through the intervertebraldisc.

FIG. 69 is an anatomic anterior perspective view showing, in an explodedview prior to implantation, assemblies comprising one or more implantstructures like that shown in FIG. 55 inserted from left and/or rightanterolateral regions of a given lumbar vertebra, in an angled paththrough the intervertebral disc and into an opposite anterolateralinterior region of the next inferior lumbar vertebra, FIG. 69 showing inparticular one implant structure entering on the right anterolateralside of L4, through the intervertebral disc and into the leftanterolateral region of L5, and one implant structure entering on theleft anterolateral side of L4, through the intervertebral disc and intothe right anterolateral region of L5, the left and right implantstructures crossing each other in transit through the intervertebraldisc.

FIG. 70 is an anatomic posterior perspective view, exploded prior toimplantation, of a representative configuration of an assembly of one ormore implant structures like that shown in FIG. 55 , sized andconfigured to achieve translaminar lumbar fusion in a non-invasivemanner and without removal of the intervertebral disc.

FIG. 71 is an anatomic inferior transverse plane view showing theassembly shown in FIG. 70 after implantation.

FIG. 72 is an anatomic posterior perspective view, exploded prior toimplantation, of a representative configuration of an assembly of one ormore implant structures like that shown in FIG. 55 , sized andconfigured to achieve lumbar facet fusion, in a non-invasive manner andwithout removal of the intervertebral disc.

FIG. 73 is an anatomic inferior transverse plane view showing theassembly shown in FIG. 72 after implantation.

FIG. 74 is an anatomic lateral view showing the assembly shown in FIG.72 after implantation.

FIG. 75A is an anatomic anterior perspective view showing, in anexploded view prior to implantation, a representative configuration ofan assembly of one or more implant structures like that shown in FIG. 55, sized and configured to achieve fusion between lumbar vertebra L5 andsacral vertebra S1, in a non-invasive manner and without removal of theintervertebral disc, using an anterior approach.

FIG. 75B is an anatomic anterior perspective view showing the assemblyshown in FIG. 75A after implantation.

FIG. 76A is an anatomic posterior view showing, in an exploded viewprior to implantation, another representative configuration of anassembly of one or more implant structures 20C sized and configured toachieve fusion between lumbar vertebra L5 and sacral vertebra S1, in anon-invasive manner and without removal of the intervertebral disc,using a postero-lateral approach entering from the posterior iliac spineof the ilium, angling through the SI-Joint, and terminating in thelumbar vertebra L5.

FIG. 76B is an anatomic posterior view showing the assembly shown inFIG. 76A after implantation.

FIG. 76C is an anatomic superior view showing the assembly shown in FIG.76B.

FIG. 77 is an anatomic lateral view showing a spondylolisthesis at theL5/S1 articulation, in which the lumbar vertebra L5 is displaced forward(anterior) of the sacral vertebra S1.

FIG. 78A is an anatomic anterior perspective view showing, in anexploded view prior to implantation, a representative configuration ofan assembly of one or more implant structures like that shown in FIG. 55, sized and configured to stabilize a spondylolisthesis at the L5/S1articulation.

FIG. 78B is an anatomic anterior perspective view showing the assemblyshown in FIG. 78A after implantation.

FIG. 78C is an anatomic lateral view showing the assembly shown in FIG.78B.

FIGS. 79A-79N illustrate an embodiment of a single bladed removalsystem.

FIGS. 80A-80D illustrate an embodiment of a double bladed removalsystem.

FIG. 81 illustrates an embodiment of an implant structure.

FIGS. 82A-82D are side section views of the formation of a broached borein bone according to one embodiment of the invention.

FIGS. 82E and 82F illustrate the assembly of a soft tissue protectorsystem for placement over a guide wire.

FIGS. 83 and 84 are, respectively, anterior and posterior anatomic viewsof the human hip girdle comprising the sacrum and the hip bones (theright ilium, and the left ilium), the sacrum being connected with bothhip bones at the sacroiliac joint (in shorthand, the SI-Joint).

FIGS. 85, 86, 87A and 87B are anatomic views showing, respectively, apre-implanted perspective, implanted perspective, implanted anteriorview, and implanted cranio-caudal section view, the implantation ofthree implant structures for the fixation of the SI-Joint using alateral approach through the ilium, the SI-Joint, and into the sacrum.

FIGS. 88A-88C illustrate an embodiment of a long implant that has beenimplanted across the sacrum. The two ilia are not shown.

FIGS. 89A-89C illustrate an embodiment of the insertion of a guide pinthrough the SI-Joints and the formation of aligned cavities in the bone.

FIGS. 90A and 90B illustrate an embodiment of a guide pin and broachwith alignment features.

DETAILED DESCRIPTION

Tissue Dilator and Protector

FIGS. 1A and 1B are a perspective view and a longitudinalcross-sectional view, respectively, of an embodiment of a dilator 10with an integrated infusion system. In some embodiments, the dilator 10can be used as a soft tissue protector in addition to or in place of itsfunction as a dilator 10. In some embodiments, the dilator 10 has alongitudinal body 12 with a wall 14 that can be shaped to match thecross-sectional profile of an implant 26. The wall 14 can define apassage that extends through the longitudinal body. For example, if theimplant 26 has a triangular cross-section, then the hollow interior ofthe dilator 10 can have a triangular cross-section that matches theimplant geometry, such that the implant 26 can pass through the interiorof the dilator 10. In other embodiments, the implant 26 can have othercross-sectional geometries, such as a square implant, a hexagonalimplant and the like, and the cross-sectional shape of the interior ofthe dilator is designed to match the implant 26. The hollow interiorcross-sectional area of the dilator is sized to be slightly larger thanthe cross-sectional area of the implant 26, which allows the implant 26to pass through the dilator with little lateral movement within thedilator 10.

In some embodiments, the exterior cross-sectional shape of the dilator10 can also match the implant 26 cross-sectional shape. In the case of atriangular implant and most non-circular implants, this allows thesurgeon to easily and accurately control the orientation that theimplant 26 will ultimately be inserted into the patient. For example,the surgeon can align the vertices of the triangular dilator in thedesired orientation and be assured that the implant 26 will be implantedin the same orientation. In other embodiments, the exteriorcross-sectional shape of the dilator 10 does not match the implant 26cross-sectional shape.

The dilator 10 has a distal end 16 and a proximal end 18, where theterms distal and proximal are used in relation to the operator of thedilator 10. In some embodiments, the distal end 16 of the dilator 10 hasa beveled edge 20. The beveled edge 20, which can be formed on theinterior surface and/or the exterior surface of the distal end 16 of thewall 14, is designed to aid in the insertion of the dilator 10 throughsoft tissue, as well as providing a way for stabilizing the dilator 10by being able to bite into the bone around the implant site. Forexample, once the dilator 10 is place against the bone in the correctorientation, the surgeon can tap the dilator 10 so that the beveled edge20 bites into the bone, thereby anchoring the dilator 10 in place.

The proximal end 18 of the dilator 10 can have a collar 22 that isattached to the longitudinal body 12. The collar 22 can be knurled toprovide a better grip for the operator. In addition, the collar 22 canhave an attachment feature, such as a threaded hole for example, toallow the attachment of a handle, with for example a correspondingthreaded end portion. In some embodiments, the attachment feature can beoriented such that the handle extends both axially and radially away inthe proximal direction from the longitudinal axis of the dilator 10.

In some embodiments, as illustrated in FIGS. 1A and 1B, the dilator 10includes one or more ports 24 that can be used for infusing and/orcoating a liquid, gel, slurry, paste, powder or other material ontoand/or into the implant 26 as the implant 26 is advanced through thedilator 10 and inserted into the patient. The ports 24 can be located onthe interior surface of the distal end 16 or distal portion of thedilator 10 such that the ports 24 face the implant 26 as the implant 26passes through the dilator 10. The ports 24 can have circular openings,oval openings, square openings, rectangular or slot openings, or anyother suitably shaped opening that is capable of coating the implantsurfaces as the implant 26 passes through the dilator 10. The number ofports 24 can vary. For example, for a triangular dilator 10 with a wall14 with three planar surfaces, the dilator 10 can have one port 24 foreach planar surface, for a total of three ports 24. In otherembodiments, each planar surface can have two or three or more ports 24.In some embodiments, the one or more ports 24 can be spaced evenlyaround the circumference of the distal portion of the dilator 10. Insome embodiments, the openings of the ports 24 extend around at least5%, 10%, 25%, 50%, 75% or 90% of the circumference of the dilator 10.For example, one or more slit type openings can be used to extendsubstantially around the circumference of the dilator 10, which willenable the implant surfaces to be coated substantially with the coatingmaterial.

In some embodiments, the ports 24 can be connected to and/or are influid communication with one or more reservoirs 28, such as a hollowtube or channel for example, that contains the coating material. Thereservoirs 28 can be integrated within the wall 14 of the dilator 10such that the reservoirs 28 are located between the inner and outersurfaces of the wall 14. The reservoirs 28 also may be connected toand/or are in fluid communication with one or more openings 30 on theproximal end 18 of the dilator 10, as shown. These openings 30 can beloading ports used for loading the coating material into the reservoir28. In addition, these openings 30 can be configured to receive, forexample, a pusher and plunger device 32 that can be inserted into theopenings 30 and push the coating material out of the reservoir 28 andout of the ports 24 to coat the implant 26. The pusher and plungerdevice 32 can also be referred to as an impactor. The pusher and plungerdevice 32 includes a pusher portion 34 that is configured to be insertedinto the dilator 10 to push the implant 26 into the patient and aplunger portion 36 that is configured to be inserted into the reservoir28 to push the coating material out of the dilator 10. The pusher andplunger device 32 can be integrated as a single device so that a singlepushing action by the operator will cause the pusher and plunger device32 to simultaneously push out the implant 26 and push out the coatingmaterial, thereby coating and/or infusing the implant 26 with thecoating material as the implant 26 is advanced out of the dilator 10 andinserted into the patient.

In some embodiments, the coating material can include a biologic aidthat can promote and/or enhance bony ingrowth, tissue repair, and/orreduce inflammation, infection and pain. For example, the biologic aidcan include growth factors, such as bone morphogenetic proteins (BMPs),hydroxyapatite in, for example, a liquid or slurry carrier,demineralized bone, morselized autograft or allograft bone, medicationsto reduce inflammation, infection or pain such as analgesics,antibiotics and steroids. In some embodiments, the growth factors can behuman recombinant growth factors, such as hr-BMP-2 and/or hr-BMP-7, orany other human recombinant form of BMP, for example. The carrier forthe biologic aid can be a liquid or gel such as saline or a collagengel, for example. The biologic aid can also be encapsulated orincorporated in a controlled released formulation so that the biologicaid is released to the patient at the implant site over a longerduration. For example, the controlled release formulation can beconfigured to release the biologic aid over the course of days or weeksor months, and can be configured to release the biologic aid overestimated time it would take for the implant site to heal. The amount ofbiologic aid delivered to the implant 26 can be controlled using avariety of techniques, such as controlling or varying the amount ofcoating material applied to the implant and/or controlling or varyingthe amount of biologic aid incorporated into the coating material. Insome embodiments, in may be important to control the amount of biologicaid delivered because excessive use of certain biologic aids can resultin negative effects such as radicular pain, for example.

The dilator 10 can be made of a variety of materials, such as metals andmetal alloys. For example, the dilator 10 can be made of a stainlesssteel or titanium alloy. In addition, the dilator 10 or parts of thedilator 10 can be made of other materials such as polymers and carbonfibers, for example.

FIGS. 2A and 2B are cross-sectional views that illustrate an embodimentof an expandable dilator 200. For example, in one embodiment of theexpandable dilator 200, the longitudinal body 202 of the dilator 200 ismade of a plurality of interconnected and slidable wall portions 204. Inthe collapsed or non-expanded configuration, the expandable dilator 200has a smaller cross-sectional area which facilitates insertion of thedilator 200 through soft tissues, causing less soft tissue damage than alarger device, and therefore, reducing pain and recovery time for thepatient. In addition, in some embodiments the smaller cross-sectionalarea in the collapsed configuration allows the dilator 200 to be used inminimally invasive procedures. In the collapsed configuration, thecross-sectional area of the expandable dilator 200 can be less than thecross-sectional area of the implant. In the expanded configuration, thecross-sectional area of the expandable dilator 200 can be slightlygreater than the cross-sectional area of the implant. The expandabledilator 200 can be expanded only when needed during the various steps ofthe overall procedure, such as during the insertion of the broach andimplant 26, thereby reducing or minimizing the time the soft tissue isfully expanded.

As illustrated in FIGS. 2A and 2B, some embodiments of the expandabledilator 200 have a triangular cross-section area. The interconnected andslidable wall portions 204 can include three inner wall portions 206 andthree outer wall portions 208. The inner wall portions 206 can besubstantially planar while the outer wall portions 208 can be angled at,for example, approximately 60 degrees to form vertices of a triangle. Inother embodiments, the outer wall portions can be substantially planarwhile the inner wall portions can be angled to form vertices of atriangle. For example, the inner wall portions 206 of the embodimentillustrated in FIGS. 2A and 2B can be moved to the outside of thedilator, while the outer wall portions 208 can be moved to the inside.

In the collapsed configuration, the inner wall portions 206 can bearranged in a triangular orientation with the outer wall portions 208placed around the outside of the inner wall portions 206 to form thevertices of the triangle. Each outer wall portion 208 is connected totwo inner wall portions 206, and each inner wall portion 206 isconnected to two outer wall portions 208. In the collapsedconfiguration, the overlap of the inner wall portion 206 with the outerwall portion 208 is at its greatest or maximum amount, with thelongitudinal edges 210 of the outer wall portion 208 near or at thecentral portion of the inner wall portion 206, and the longitudinaledges 212 of the inner wall portion near or at the vertices 214 of theouter wall portions 208.

In some embodiments, the inner wall portions 206 and the outer wallportions 208 of the dilator 200 define a lumen 209 that is configured toreceive a plurality of different surgical tools and devices, such as aguide pin and guide pin sleeve. In some embodiments, the guide pinsleeve has a similar cross-sectional shape and size as the lumen 209 ofthe expandable dilator 200, which allows the guide pin sleeve to fitsecurely within the lumen 209. Additional surgical tools and devices canbe inserted into the dilator 200 over the guide pin and/or guide pinsleeve, causing the dilator 200 to expand to accommodate the additionaltools and devices.

An outward force applied to the inner surfaces of the dilator 200 can beused to expand the collapsed configuration to the expanded configurationvia a slide and lock mechanism, for example. The inner wall portions 206can be slidably secured to the outer wall portions 208 by a variety oftechniques, such as a dovetail fit between the wall portions. Asillustrated in FIG. 2C, a locking mechanism can be used to keep the wallportions from over expanding and separating. For example, thelongitudinal edges 212 of the inner wall portions 206 can have a latchportion 216 while the longitudinal edges 210 of the outer wall portions208 can have a corresponding groove portion 218. When the dilator 200 isfully expanded, the latch portions 216 fall or snap into thecorresponding groove portions 218 and stop or inhibit further expansionof the dilator. The latch portion 216 and groove portions 218 can havecorresponding bevels that allow the dilator 200 to be collapsed backinto the collapsed configuration from the fully expanded configuration.For example, a bevel 220 on the outer longitudinal edge of the latchportion 216 and a bevel 222 on the inner longitudinal edge of the grooveportion will allow the dilator 200 to collapse from the fully expandedconfiguration.

Other dilator 200 geometries can be used in place of the triangulardilator 200 illustrated in FIGS. 2A and 2B. For example, FIGS. 2D and 2Eillustrate an expandable dilator 200 with a substantially circularcross-sectional area when expanded. FIGS. 2F and 2G illustrate anexpandable dilator 200 with a substantially square cross-sectional areawhen expanded. Similarly, other geometries can be used, such as arectangle, oval, hexagon, and the like.

FIGS. 3A and 3B illustrate another embodiment of the dilator 300. Thedilator 300 comprises a longitudinal body 302 with a proximal end 304and a distal end 306. The longitudinal body 302 gradually tapers to arounded portion 322 or a narrow portion at the distal end 306, therebyforming a tapered portion 308. The rounded portion 322 or narrow portionat the distal end 306 is more easily pushed over the guide pin or guidewire through the soft tissue, reducing the possible tissue damage thatcan be caused by pushing a larger diameter or larger cross-sectionalarea dilator through the soft tissue. As the dilator 300 is pushedfurther into the soft tissue, the widening cross-sectional area of thetapered portion 308 gradually pushes the soft tissue apart.

The tapered portion 308 of the longitudinal body 302 has a plurality ofslits 310 that extend from the distal end 306 to a stress relief portion312 on the proximal end of the tapered portion 308. The plurality ofslits 310 divide the tapered portion into expandable blade portions 314that can be pushed, moved, actuated or rotated outwards to expand theinterior diameter and cross-sectional area of the tapered portion 308.In some embodiments, the dilator 300 has two slits, while in otherembodiments, the dilator 300 has 3, 4, or more slits which can be evenlyspaced around the circumference of the tapered portion 308. In someembodiments, the slits can be aligned with the corners of thelongitudinal body 302, such as the apexes of a triangular shapedlongitudinal body 302. In other embodiments, the slits can be aligned inbetween the corners of the longitudinal body 302. For example, in someembodiments, a triangular dilator 300 with three sides can have threeslits to divide the tapered portion into three blade portions. Therounded portion 322 or narrow portion can have a hole or cutout at thecentral and distal most point or portion that aligns with thelongitudinal axis of the dilator 300 in order to facilitate the passageof a guide pin or guide wire through the dilator 300.

In some embodiments, the stress relief portion 312 can be a cutout orhole in the longitudinal body 302 that facilitates the movement of theblade portions 314 from a non-expanded configuration to an expandedconfiguration. The blade portions 314 can be pushed apart into theexpanded configuration by mechanical means, such as by the insertion ofan inner tube 316 that slides into the interior of the dilator 300. Insome embodiments, the inner tube 316 is a guide tube that facilitatesthe passage of another device, such as a drill bit or broach or implant,through the dilator 300. As the inner tube is advanced through theinterior of the dilator 300, the distal end of the inner tube 316contacts the inner surface of the blade portions 314 and progressivelypushes the blade portions 314 apart until the inner diameter of thedilator 300 is at least as great as the outer diameter of the inner tube316. The inner tube 316 can have a collar portion 318 that is configuredto abut against the proximal end 304 of the dilator 300 when the innertube 316 is fully inserted into the dilator 300. At full insertion, thedistal end 320 of the inner tube 316 can extend to the distal end 306 ofthe dilator 300, or extend to a point just proximal the distal end 306of the dilator 300.

In some embodiments, the expandable dilator 300 can be made of metals orpolymers, for example. The material of the blade portions 314 that bendsand/or deforms can be resiliently or non-resiliently flexible. Inaddition, in some embodiments, the deformation of the blade portions 314can be substantially permanent in the sense that once expanded, theblade portions 314 tend to stay in the expanded configuration and resistcompression even if the inner tube 316 is removed. In other embodiments,the deformation of the blade portions 314 can be substantiallyreversible in the sense that once expanded, the blade portions 314 tendto want to return to the original non-expanded configuration.

In other embodiments, as illustrated in FIG. 3C, the blade portions 314can be attached or connected to the longitudinal body 302 with a hingeor other mechanical means that allows the blade portions 314 to bendoutwards. As mentioned above, the blade portions can also oralternatively be made of a flexible material. Also, the tapered portion308 can be of different lengths, and illustrated in FIGS. 3A to 3C. FIG.3A illustrates a relatively longer tapered portion 308 that forms atleast half of the overall length of the longitudinal body 302. Incontrast, FIG. 3C illustrates a relatively short tapered portion 308that is only located on the distal portion of the device, and forms lessthan half of the overall length of the longitudinal body 302, such asless than about 30%, less than about 20% or less than about 10% of theoverall length of the longitudinal body 302.

In some embodiments, the dilator 300 can instead be used as a deliverysheath or sleeve that covers the implant 26. The sheath or sleeveembodiment can be used, for example, when the implant 26 includes anintegrated broach portion on the distal end of the implant 26. In someembodiments, the sheath or sleeve embodiment has a tapered portion 308that substantially matches the taper of the broach. In some embodiments,the implant 26, rather than an inner tube 316, is used to push open theblade portions 314. In some embodiments, the broach portion of animplant 26 with an integrated broach portion is used to push open theblade portions 314.

FIGS. 4A and 4B show an embodiment of a delivery sleeve 400 that can beused in place of a dilator and/or soft tissue protector. The deliverysleeve 400 can be made to fit over the implant 26 and have a tapereddistal end 402 that can expand outwards to allow the implant 26 to passthrough the delivery sleeve 400. The delivery sleeve 400 can be flexibleso that the tapered distal end 402 can be expanded to allow the implant26 to pass through. The tapered distal end 402 can include a pluralityof slits 414 that divide the tapered distal end into blade portions 416in a similar manner as described above for the dilators. The slits 414can be aligned in a variety of ways, such as being aligned with thevertices or being aligned between the vertices. A variety of flexiblematerials can be used to fabricate the delivery sleeve 400, such asnitinol or another flexible metal or metal allow, or flexible nonmetalmaterials such as polymers. The delivery sleeve 400 can be shaped asdescribed herein for dilators and other delivery sleeves. For example,the delivery sleeve 400 can be triangular shaped with a triangularcross-section for a triangular shaped implant 26 with a triangularcross-section. An impactor 404 sized to fit within the delivery sleeve400 can be used to push the implant 26 out of the delivery sleeve 400and into the implant site. In some embodiments, the delivery sleeve 400is used to cover the implant 26 only during insertion of the implant 26into the implant site.

In addition, in some embodiments, an adjusting sleeve 406 is configuredto fit within the delivery sleeve 400 so that a variety of differentlength implants 26 can be used with a single length delivery sleeve 400.In some embodiments, the delivery sleeve 400 can have a threaded nut 408located on the proximal end 410 of the delivery sleeve 400. Theadjusting sleeve 406 can have corresponding external threads 412 on itsouter surface and be sized to fit through the inner diameter of the nut408 so that the external threads 412 on the adjusting sleeve 406 engagethe internal threads on the nut 408. Once the threads are engaged, theadjusting sleeve 406 can be rotated relative to the nut 408 in order toadvance or retract the adjusting sleeve 406 through the delivery sleeve400. In other embodiments, the adjusting sleeve 406 can be adjusted witha ratcheting mechanism that is advanced via translation, such as pushingor pulling, as opposed to rotation. For example, the ratchetingmechanism can include a plurality of teeth on the adjusting sleeve 406and a pawl on the delivery sleeve.

The adjusting sleeve 406 can be advanced to the implant 26 so that thedistal end of the adjusting sleeve 406 abuts against the proximal end ofthe implant 26. In addition, the adjusting sleeve 406 can be advanced sothat the implant 26 is pushed to or near the distal end 402 of thedelivery sleeve 400. In order to expand the tapered distal end 402 ofthe delivery sleeve 400, the adjusting sleeve 406 can be furtheradvanced through the delivery sleeve 400, thereby pushing the implant 26so that the distal end of the implant 26 pushes apart the tapered distalend 402 of the delivery sleeve 400. The impactor 404 can be sized to fitthrough the adjusting sleeve 406. In addition, the system as describedcan be used with one or more of the following: a guide pin or guidewire, drill sleeve, drill, broach sleeve and broach, for example.

In some embodiments, the triangular delivery sleeve 400 is designed togo over a guide pin and then expand to dilate the soft tissues. Asillustrated in FIG. 4B, the distal portion of the delivery sleeve 400can include three rigid blade portions or arms 416 that cover each apexof the triangular shape. These arms 416 move in the direction of thesmall outward arrows when the nut or dial 408 in the proximal portion ofthe delivery sleeve 400 rotates by a predetermined amount, for example,by about 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 degrees. The dial 408has rigid pins 418 which engage a path on the rigid arms 416 that forcethe rigid arms 416 to expand or collapse when the dial 408 is rotated.Three of the small circles 420 represent the rigid pins 416 in position1, where the delivery sleeve 400 is in the relaxed step, with the arms416 in a collapsed configuration, during initial insertion. The threeother circles 422 represent the rigid pins 416 in position 2 where theyhave expanded the rigid arms 416 (expansion of arms not shown).

FIGS. 5A-5C illustrate an embodiment of a sequential dilation system. Aguide pin 500 can be placed into the bone. In some embodiments, theguide pin 500 can have a cannula 502 or sleeve that covers at least thedistal portion of the guide pin 500 prior to insertion. After the guidepin 500 is inserted into the bone at the right location and depth, thecannula 502 can be removed from the guide pin 500. In some embodiments,the distal portion of the guide pin 500 can include a plurality ofprongs 504 that expand or curl outwards once removed from the cannula502. The prongs 504 can form an anchor in the bone that anchors andprevents or inhibits further advancement of the guide pin 500 within thebone.

After the guide pin 500 has been inserted into the bone and the cannula502 has been removed, a sequence of dilators can be inserted over theguide pin 500 in order to gradually dilate the soft tissue and to servelater as a guide for insertion of additional instruments and devices.For example, in some embodiments a drill dilator 506 can be insertedover the guide pin 500 to dilate the soft tissue. Additional dilatorsinclude, for example, a broach dilator 508 that can be placed over thedrill dilator 506 and be shaped to match the cross-sectional shape ofthe broach and implant. For example, the broach dilator 508 can have atriangular cross section for a triangular implant. Placement of thebroach dilator 508 over the drill dilator 506 further dilates the softtissue around the guide pin 500. In addition, an outer cannula 510 thatis shaped and sized to fit over the broach dilator 508 can be placedover the broach dilator 508 to further dilate the soft tissue and tocomplete the dilator system assembly.

In order to drill a hole through the bone around the guide pin 500, thedrill dilator 506 can be removed. The drill dilator 506 can be sized tocorrespond to the diameter of the drill bit. Once the drill dilator 506is removed, the broach dilator 508 and the space vacated by the drilldilator 506 forms a guide for the drill bit. After the hole is drilled,the broach dilator 508 can be removed. The outer cannula 510 and thespace vacated by the broach dilator 508 forms a guide for a broach whichwidens the hole drilled into the bone into a hole shaped to receive theimplant.

In some embodiments, the outer cannula 510 can include one or morestabilizing pins 512 that can be located around the circumference of theouter cannula 510. For example, a triangular shaped outer cannula 510can have three stabilizing pins 512, with one stabilizing pin 512located at each apex of the triangular cannula 510. The stabilizing pins512 are aligned longitudinally along the outer cannula, with forexample, the apexes of the triangular outer cannula 510 and/or the facesor flat portions of the outer cannula 510. The stabilizing pins 512 canbe located in a channel or tube on the outer cannula 510, for example,and can be deployed into the bone after the outer cannula 510 ispositioned over the guide pin and other dilators and into contact withthe bone around the implant site. In some embodiments, the channel ortubes holding the stabilizing pins 512 are located on the outer surfaceof the outer cannula 510, while in other embodiments the channel ortubes are embedded within the outer cannula 510 walls. Deployment of thestabilizing pins 512 into the bone around the implant site providesadditional stability to the dilator system, thereby reducing unwanted orinadvertent movement of the system during the implant insertion processand resulting in accurate placement of the implant in bone.

In some embodiments, the dilators and cannulas can be radiolucent and bemade from radiolucent materials such as polymers or a carbon fiber basedmaterial. In general, instruments and devices that do not substantiallyenter the bone can be radiolucent in some embodiments, while instrumentsand devices that do substantially enter the bone can be radiopaque. Thisproperty of being radiolucent or radiopaque is applicable to all theembodiments disclosed herein.

For example, the drill dilator 506, the broach dilator 508 and the outercannula 510 can be radiolucent, while the guide pin 500 and the implantcan be radiopaque. In some embodiments, the stabilizing pins 512 canalso be radiopaque. This allows the surgeon to monitor usingfluoroscopy, for example, the position of the guide pin 500 and implantin the bone during the insertion procedure without being obscured by thedilators and cannulas, thereby reducing the likelihood that the guidepin 500 or implant is inserted into the wrong location, which can damagesensitive tissues such as blood vessels and nerves, and require theremoval and reinsertion of the implant.

FIGS. 6A-6D illustrate embodiments of a quick change mechanism thatallows two instruments or components to be quickly and reversiblyconnected together. Although the quick change or quick connect mechanismwill now be described for a handle and a dilator, it should beunderstood that the quick change or quick connect mechanism can be usedto connect many other types of instruments or components together. Asshown in FIGS. 6A and 6B, a dilator 600 can be attached to a handle 602using a bayonet-type connector. The bayonet connector can include, forexample, a pin 604 or tab located on the distally located handleattachment portion 605 that is configured to fit into an L or J shapedslot 606 in the proximally located dilator attachment portion 608. Inother embodiments, the pin 604 can be located on the dilator 600 and theL shaped slot 606 can be located on the handle 602. The L shaped slot606 has an axially aligned slot portion 610 that is configured toreceive the pin 604, and a transversely aligned slot portion 612 that isconfigured to reversibly lock the pin 604 in place in some embodiments.In some embodiments, the transversely aligned slot portion 612 can beangled or curved towards the proximal end of the dilator. One end of thetransversely aligned slot portion 612 is connected to the axiallyaligned slot portion 610. In some embodiments, a locking slot portion614 is located on the other end of the transversely aligned slot portion612. The locking slot portion 614 extends axially and towards theproximal end of the dilator 600 and is configured to securely andreversibly lock the pin 604 in place. In some embodiments where thetransversely aligned slot portion 612 is angled or curved towards theproximal end of the dilator 600, the transversely aligned slot portion612 can also function as the locking slot portion.

To connect the dilator 600 to the handle 602, the pin 604 is alignedwith and then inserted into the axially aligned slot portion 610 of theslot 606. Once the pin 604 reaches the end of the axially aligned slotportion 610, the handle 602 is rotated or twisted relative to thedilator 600 about the longitudinal axis, thereby moving the pin 604along the transversely aligned slot portion 612. Once the pin 604reaches the end of the transversely aligned slot portion 612, a spring,which can be constantly applying a force or tension on the pin 604towards the proximal end of the dilator 600, pushes and secures the pin604 into the locking slot portion 614. Once in the locking slot portion614, the pin 604 is restricted from moving in the transverse directionas well as in the axial direction towards the proximal end of thedilator.

To remove the dilator 600 from the handle 602, the pin 604 is pushedaxially towards the distal end of the dilator, thereby moving the pinout 604 out of the locking slot portion 614. Next, the pin 604 isrotated along the transversely aligned slot portion 612 until the pin604 reaches the axially aligned slot portion 610. Once the pin 604reaches the axially aligned slot portion 610, the pin 604 can be removedfrom the L shaped slot, thereby disconnecting the handle 602 from thedilator 600. As mentioned above, portions of the dilator 600 and handle602, such as collar portions, can be knurled to provide an enhancedgripping feature.

An embodiment of an alternative quick connect mechanism is illustratedin FIGS. 6C and 6D. In some embodiments, this mechanism includes atleast one spring loaded pin 616 or spring loaded bearing that is locatedon the inner circumference of the handle attachment portion 605. In someembodiments, the mechanism includes a plurality of spring loaded pins616, such as 2, 3 or 4 or more spring loaded pins 616. In someembodiments, the dilator 600 can include pin receptacles 618 that areconfigured to receive the spring loaded pins 616. In addition, thedilator 600 can include a pin groove 620 that is configured to receivethe spring loaded pins 616. The pin groove 620 can be configured toalign the spring loaded pins 616 with the pin receptacles 618. In someembodiments, the pin receptacles 618 are located along the pin groove620, and the depth of the pin receptacles 618 is generally greater thanthe depth of the pin groove 620. In other embodiments, the spring loadedpins 616 can be located on the dilator 600 while the pin receptacles 618and pin groove 620 can be located on the handle 602.

To connect the dilator 600 to the handle 602, the spring loaded pins 616can be aligned with the pin receptacles 618. The handle 602 and dilator600 can then be pushed together. As the handle 602 and dilator 600 arepushed together, the spring loaded pins 616 are initially pushed backinto the handle 602 so that the handle 602 can slide over the dilator600. Once the spring loaded pins 616 are aligned over the pinreceptacles 618 or pin groove 620, the spring loaded pins 616 push backout from the handle and into the pin receptacles 618 or pin groove 620on the dilator 600. If the spring loaded pins 616 are in the pin groove620, the spring loaded pins 616 can be rotated along the pin groove 620until the spring loaded pins 616 are aligned with the pin receptacles618. Once aligned, the spring loaded pins 616 push into pin receptacles618, thereby reversibly locking the dilator 600 and handle 602 together.

In some embodiments, to remove the dilator 600 from the handle 602, thedilator 600 and handle 602 can be simply be pulled apart, with orwithout rotation depending on the embodiment. As force is exerted on thespring loaded pins 616 in the pin receptacles 618, the spring loadedpins 616 begin to be pushed back into the handle 602. Once enough forceis exerted on the spring loaded pins 616, from a pulling force and/orrotational force, the spring loaded pins 616 will retract back into thehandle 606 and allow the dilator 600 to be separated from the handle602. In other embodiments, the handle 602 can have a pin retractor thatcan be actuated to temporarily retract the spring loaded pins 616 intothe handle 602. The pin retractor can be actuated prior to either handle602 connection or handle 602 removal to ease connection and removal ofthe handle 602 from the dilator.

The soft tissue protectors, dilators, delivery sleeves and quick connectmechanisms described above can be used with a variety of implants in avariety of implant procedures, examples of which are further describedbelow.

Elongated, stem-like implant structures 1020 like that shown in FIG. 7make possible the fixation of the SI-Joint (shown in anterior andposterior views, respectively, in FIGS. 9 and 10 ) in a minimallyinvasive manner. These implant structures 1020 can be effectivelyimplanted through the use a lateral surgical approach. The procedure isdesirably aided by conventional lateral and/or anterior-posterior (A-P)visualization techniques, e.g., using X-ray image intensifiers such as aC-arms, intraoperative CT scanners, or fluoroscopes to produce a liveimage feed which is displayed on a TV screen.

In one embodiment of a lateral approach (see FIGS. 11, 12, and 13A/B),one or more implant structures 1020 are introduced laterally through theilium, the SI-Joint, and into the sacrum. This path and resultingplacement of the implant structures 1020 are best shown in FIGS. 12 and13A/B. In the illustrated embodiment, three implant structures 1020 areplaced in this manner. Also in the illustrated embodiment, the implantstructures 1020 are rectilinear in cross section and triangular in thiscase, but it should be appreciated that implant structures 1020 of othercross sections can be used. For example, the implant structures can havea square cross-section. In some embodiments, the implant structures canhave a curvilinear cross-section, such as circular, oval or elliptical.The cross-sections discussed above refer to the transverse cross-sectionof the implant rather than a longitudinal cross-section taken along thelongitudinal axis of the implant structure. In addition, the termrectilinear describes a device that is defined or substantially definedby straight lines. This includes, for example, triangles, squares, andother polygons, and also includes triangles, squares and other polygonshaving rounded corners. In contrast, the term curvilinear is meant todescribe devices that are defined by only curved lines, such as a circleor ellipse, for example.

Before undertaking a lateral implantation procedure, the physicianidentifies the SI-Joint segments that are to be fixated or fused(arthrodesed) using, e.g., the Fortin finger test, thigh thrust, FABER,Gaenslen's, compression, distraction, and diagnostic SI joint injection.

Aided by lateral and anterior-posterior (A-P) c-arm images, and with thepatient lying in a prone position, the physician aligns the greatersciatic notches (using lateral visualization) to provide a true lateralposition. A 3 cm incision is made starting aligned with the posteriorcortex of the sacral canal, followed by blunt tissue separation to theilium. From the lateral view, the guide pin 1038 (with sleeve (notshown)) (e.g., a Steinmann Pin) is started resting on the ilium at aposition inferior to the sacrum end plate and just anterior to thesacral canal. In A-P and lateral views, the guide pin 1038 should beparallel to the sacrum end plate at a shallow angle anterior (e.g.,15.degree. to 20.degree. off horizontal, as FIG. 13A shows). In alateral view, the guide pin 1038 should be posterior to the sacrumanterior wall. In the A-P view, the guide pin 1038 should be superior tothe sacral inferior foramen and lateral of mid-line. This correspondsgenerally to the sequence shown diagrammatically in FIGS. 8A and 8B. Asoft tissue protector (not shown) is desirably slipped over the guidepin 1038 and firmly against the ilium before removing the guide pinsleeve (not shown).

Over the guide pin 1038 (and through the soft tissue protector), thepilot bore 1042 is drilled in the manner previously described, as isdiagrammatically shown in FIG. 8C. The pilot bore 1042 extends throughthe ilium, through the SI-Joint, and into the S1. The drill bit 1040 isremoved.

The shaped broach 1044 is tapped into the pilot bore 1042 over the guidepin 1038 (and through the soft tissue protector) to create a broachedbore 1048 with the desired profile for the implant structure 1020,which, in the illustrated embodiment, is triangular. This generallycorresponds to the sequence shown diagrammatically in FIG. 8D. Thetriangular profile of the broached bore 1048 is also shown in FIG. 11 .

FIGS. 8E and 8F illustrate an embodiment of the assembly of a softtissue protector or dilator or delivery sleeve 800 with a drill sleeve802, a guide pin sleeve 804 and a handle 806. In some embodiments, thedrill sleeve 802 and guide pin sleeve 804 can be inserted within thesoft tissue protector 800 to form a soft tissue protector assembly 810which can slide over the guide pin 808 until bony contact is achieved.The soft tissue protector 800 can be any one of the soft tissueprotectors or dilators or delivery sleeves disclosed herein. In someembodiments, an expandable dilator or delivery sleeve 800 as disclosedherein can be used in place of a conventional soft tissue dilator. Inthe case of the expandable dilator, in some embodiments, the expandabledilator can be slid over the guide pin and then expanded before thedrill sleeve 802 and/or guide pin sleeve 804 are inserted within theexpandable dilator. In other embodiments, insertion of the drill sleeve802 and/or guide pin sleeve 804 within the expandable dilator can beused to expand the expandable dilator.

In some embodiments, a dilator can be used to open a channel though thetissue prior to sliding the soft tissue protector assembly 810 over theguide pin. The dilator(s) can be placed over the guide pin, using forexample a plurality of sequentially larger dilators or using anexpandable dilator. After the channel has been formed through thetissue, the dilator(s) can be removed and the soft tissue protectorassembly can be slid over the guide pin. In some embodiments, theexpandable dilator can serve as a soft tissue protector after beingexpanded. For example, after expansion the drill sleeve and guide pinsleeve can be inserted into the expandable dilator.

As shown in FIGS. 11 and 12 , a triangular implant structure 1020 can benow tapped through the soft tissue protector over the guide pin 1038through the ilium, across the SI-Joint, and into the sacrum, until theproximal end of the implant structure 1020 is flush against the lateralwall of the ilium (see also FIGS. 13A and 13B). The guide pin 1038 andsoft tissue protector are withdrawn, leaving the implant structure 1020residing in the broached passageway, flush with the lateral wall of theilium (see FIGS. 13A and 13B). In the illustrated embodiment, twoadditional implant structures 1020 are implanted in this manner, as FIG.12 best shows. In other embodiments, the proximal ends of the implantstructures 1020 are left proud of the lateral wall of the ilium, suchthat they extend 1, 2, 3 or 4 mm outside of the ilium. This ensures thatthe implants 1020 engage the hard cortical portion of the ilium ratherthan just the softer cancellous portion, through which they mightmigrate if there was no structural support from hard cortical bone. Thehard cortical bone can also bear the loads or forces typically exertedon the bone by the implant 1020.

The implant structures 1020 are sized according to the local anatomy.For the SI-Joint, representative implant structures 1020 can range insize, depending upon the local anatomy, from about 35 mm to about 60 mmin length, and about a 7 mm inscribed diameter (i.e. a triangle having aheight of about 10.5 mm and a base of about 12 mm). The morphology ofthe local structures can be generally understood by medicalprofessionals using textbooks of human skeletal anatomy along with theirknowledge of the site and its disease or injury. The physician is alsoable to ascertain the dimensions of the implant structure 1020 basedupon prior analysis of the morphology of the targeted bone using, forexample, plain film x-ray, fluoroscopic x-ray, or MRI or CT scanning.

Using a lateral approach, one or more implant structures 1020 can beindividually inserted in a minimally invasive fashion across theSI-Joint, as has been described. Conventional tissue access tools,obturators, cannulas, and/or drills can be used for this purpose.Alternatively, the novel tissue access tools described above and inFIGS. 1-6 can also be used. No joint preparation, removal of cartilage,or scraping are required before formation of the insertion path orinsertion of the implant structures 1020, so a minimally invasiveinsertion path sized approximately at or about the maximum outerdiameter of the implant structures 1020 can be formed.

The implant structures 1020 can obviate the need for autologous bonegraft material, additional pedicle screws and/or rods, hollow modularanchorage screws, cannulated compression screws, threaded cages withinthe joint, or fracture fixation screws. Still, in the physician'sdiscretion, bone graft material and other fixation instrumentation canbe used in combination with the implant structures 20.

In a representative procedure, one to six, or perhaps up to eight,implant structures 1020 can be used, depending on the size of thepatient, the number of SI Joints treated, and the size of the implantstructures 1020. After installation, the patient would be advised toprevent or reduce loading of the SI-Joint while fusion occurs. Thiscould be about a three to twelve week period or more, depending on thehealth of the patient and his or her adherence to post-op protocol.

The implant structures 1020 make possible surgical techniques that areless invasive than traditional open surgery with no extensive softtissue stripping. The lateral approach to the SI-Joint provides astraightforward surgical approach that complements the minimallyinvasive surgical techniques. The profile and design of the implantstructures 1020 minimize or reduce rotation and micromotion. Rigidimplant structures 1020 made from titanium provide immediate post-op SIJoint stability. A bony in-growth region 1024 comprising a porous plasmaspray coating with irregular surface supports stable bonefixation/fusion. The implant structures 1020 and surgical approachesmake possible the placement of larger fusion surface areas designed tomaximize post-surgical weight bearing capacity and provide abiomechanically rigorous implant designed specifically to stabilize theheavily loaded SI-Joint.

Systems and Methods for Implanting Bone Graft and Implant

Elongated, stem-like implant structures 20A like that shown in FIG. 14make possible the fixation of the SI-Joint (shown in anterior andposterior views, respectively, in FIGS. 16 and 17 ) in a minimallyinvasive manner. These implant structures 20A can be effectivelyimplanted through the use a lateral surgical approach. The procedure isdesirably aided by conventional lateral, inlet, and outlet visualizationtechniques, e.g., using X-ray image intensifiers such as a C-arms orfluoroscopes to produce a live image feed, which is displayed on a TVscreen.

In one embodiment of a lateral approach (see FIGS. 18, 19, and 20A/B),one or more implant structures 20A are introduced laterally through theilium, the SI-Joint, and into the sacrum. This path and resultingplacement of the implant structures 20A are best shown in FIGS. 19 and20A/B. In the illustrated embodiment, three implant structures 20A areplaced in this manner. Also in the illustrated embodiment, the implantstructures 20A are rectilinear in cross section and triangular in thiscase, but it should be appreciated that implant structures 20A of otherrectilinear cross sections can be used.

Before undertaking a lateral implantation procedure, the physicianidentifies the SI-Joint segments that are to be fixated or fused(arthrodesed) using, e.g., the Fortin finger test, thigh thrust, FABER,Gaenslen's, compression, distraction, and diagnostic SI joint injection.

Aided by lateral, inlet, and outlet C-arm views, and with the patientlying in a prone position, the physician aligns the greater sciaticnotches and then the alae (using lateral visualization) to provide atrue lateral position. A 3 cm incision is made starting aligned with theposterior cortex of the sacral canal, followed by blunt tissueseparation to the ilium. From the lateral view, the guide pin 38A (withsleeve (not shown)) (e.g., a Steinmann Pin) is started resting on theilium at a position inferior to the sacrum end plate and just anteriorto the sacral canal. In the outlet view, the guide pin 38A should beparallel to the sacrum end plate at a shallow angle anterior (e.g.,15.degree. to 20.degree. off the floor, as FIG. 20A shows). In a lateralview, the guide pin 38A should be posterior to the sacrum anterior wall.In the outlet view, the guide pin 38A should be superior to the firstsacral foramen and lateral of mid-line. This corresponds generally tothe sequence shown diagrammatically in FIGS. 15A and 15B. A soft tissueprotector (not shown) is desirably slipped over the guide pin 38A andfirmly against the ilium before removing the guide pin sleeve (notshown).

Over the guide pin 38A (and through the soft tissue protector), thepilot bore 42A is drilled in the manner previously described, as isdiagrammatically shown in FIG. 15C. The pilot bore 42A extends throughthe ilium, through the SI-Joint, and into the S1. The drill bit 40A isremoved.

The shaped broach 44A is tapped into the pilot bore 42A over the guidepin 38A (and through the soft tissue protector) to create a broachedbore 48A with the desired profile for the implant structure 20A, which,in the illustrated embodiment, is triangular. This generally correspondsto the sequence shown diagrammatically in FIG. 15D. The triangularprofile of the broached bore 48A is also shown in FIG. 18 .

FIGS. 15E and 15F illustrate an embodiment of the assembly of a softtissue protector or dilator or delivery sleeve 200A with a drill sleeve202A, a guide pin sleeve 204A and a handle 206A. In some embodiments,the drill sleeve 202A and guide pin sleeve 204A can be inserted withinthe soft tissue protector 200A to form a soft tissue protector assembly210A that can slide over the guide pin 208A until bony contact isachieved. The soft tissue protector 200A can be any one of the softtissue protectors or dilators or delivery sleeves disclosed herein. Insome embodiments, an expandable dilator or delivery sleeve 200A asdisclosed herein can be used in place of a conventional soft tissuedilator. In the case of the expandable dilator, in some embodiments, theexpandable dilator can be slid over the guide pin and then expandedbefore the drill sleeve 202A and/or guide pin sleeve 204A are insertedwithin the expandable dilator. In other embodiments, insertion of thedrill sleeve 202A and/or guide pin sleeve 204A within the expandabledilator can be used to expand the expandable dilator.

In some embodiments, a dilator can be used to open a channel though thetissue prior to sliding the soft tissue protector assembly 210A over theguide pin. The dilator(s) can be placed over the guide pin, using forexample a plurality of sequentially larger dilators or using anexpandable dilator. After the channel has been formed through thetissue, the dilator(s) can be removed and the soft tissue protectorassembly can be slid over the guide pin. In some embodiments, theexpandable dilator can serve as a soft tissue protector after beingexpanded. For example, after expansion the drill sleeve and guide pinsleeve can be inserted into the expandable dilator.

As shown in FIGS. 18 and 19 , a triangular implant structure 20A can benow tapped through the soft tissue protector over the guide pin 38Athrough the ilium, across the SI-Joint, and into the sacrum, until theproximal end of the implant structure 20A is flush against the lateralwall of the ilium (see also FIGS. 20A and 20B). The guide pin 38A andsoft tissue protector are withdrawn, leaving the implant structure 20residing in the broached passageway, flush with the lateral wall of theilium (see FIGS. 13A and 13B). In the illustrated embodiment, twoadditional implant structures 20A are implanted in this manner, as FIG.19 best shows. In other embodiments, the proximal ends of the implantstructures 20A are left proud of the lateral wall of the ilium, suchthat they extend 1, 2, 3 or 4 mm outside of the ilium. This ensures thatthe implants 20A engage the hard cortical portion of the ilium ratherthan just the softer cancellous portion, through which they mightmigrate if there was no structural support from hard cortical bone. Thehard cortical bone can also bear the loads or forces typically exertedon the bone by the implant 20A.

The implant structures 20A are sized according to the local anatomy. Forthe SI-Joint, representative implant structures 20A can range in size,depending upon the local anatomy, from about 35 mm to about 60 mm inlength, and about a 7 mm inscribed diameter (i.e. a triangle having aheight of about 10.5 mm and a base of about 12 mm). The morphology ofthe local structures can be generally understood by medicalprofessionals using textbooks of human skeletal anatomy along with theirknowledge of the site and its disease or injury. The physician is alsoable to ascertain the dimensions of the implant structure 20A based uponprior analysis of the morphology of the targeted bone using, forexample, plain film x-ray, fluoroscopic x-ray, or MRI or CT scanning.

Using a lateral approach, one or more implant structures 20A can beindividually inserted in a minimally invasive fashion across theSI-Joint, as has been described. Conventional tissue access tools,obturators, cannulas, and/or drills can be used for this purpose.Alternatively, the novel tissue access tools described above and in U.S.Application No. 61/609,043, titled “TISSUE DILATOR AND PROTECTER” andfiled Mar. 9, 2012, which is hereby incorporated by reference in itsentirety, can also be used. No joint preparation, removal of cartilage,or scraping are required before formation of the insertion path orinsertion of the implant structures 20A, so a minimally invasiveinsertion path sized approximately at or about the maximum outerdiameter of the implant structures 20A can be formed.

The implant structures 20A can obviate the need for autologous bonegraft material, additional pedicle screws and/or rods, hollow modularanchorage screws, cannulated compression screws, threaded cages withinthe joint, or fracture fixation screws. Still, in the physician'sdiscretion, bone graft material and other fixation instrumentation canbe used in combination with the implant structures 20A.

In a representative procedure, one to six, or perhaps up to eight,implant structures 20A can be used, depending on the size of the patientand the size of the implant structures 20A. After installation, thepatient would be advised to prevent or reduce loading of the SI-Jointwhile fusion occurs. This could be about a six to twelve week period ormore, depending on the health of the patient and his or her adherence topost-op protocol.

The implant structures 20A make possible surgical techniques that areless invasive than traditional open surgery with no extensive softtissue stripping. The lateral approach to the SI-Joint provides astraightforward surgical approach that complements the minimallyinvasive surgical techniques. The profile and design of the implantstructures 20A minimize or reduce rotation and micromotion. Rigidimplant structures 20A made from titanium provide immediate post-op SIJoint stability. A bony in-growth region 24A comprising a porous plasmaspray coating with irregular surface supports stable bonefixation/fusion. The implant structures 20A and surgical approaches makepossible the placement of larger fusion surface areas designed tomaximize post-surgical weight bearing capacity and provide abiomechanically rigorous implant designed specifically to stabilize theheavily loaded SI-Joint.

To improve the stability and weight bearing capacity of the implant, theimplant can be inserted across three or more cortical walls. Forexample, after insertion the implant can traverse two cortical walls ofthe ilium and at least one cortical wall of the sacrum. The corticalbone is much denser and stronger than cancellous bone and can betterwithstand the large stresses found in the SI-Joint. By crossing three ormore cortical walls, the implant can spread the load across more loadbearing structures, thereby reducing the amount of load borne by eachstructure. In addition, movement of the implant within the bone afterimplantation is reduced by providing structural support in threelocations around the implant versus two locations.

In some embodiments, it may be desirable to add a bone graft materialand/or biologic aid along with the implant in order to promote bonegrowth around and/or into the implant. An embodiment of a modifiedbroach 800A is illustrated in FIGS. 21A and 21B. The modified broach800A can be used in place of the broach 44A illustrated in FIG. 15D tocreate a shaped bore with channels for receiving a bone graft materialand/or biologic aid.

The modified broach 800A can have a cross-sectional profile thatgenerally matches the shape of the implant. For example, for atriangular shaped implant, the modified broach 800A can have a generallytriangular shaped cross-sectional profile. Likewise, for an implant witha rectangular, square, or any other rectilinear shape, the modifiedbroach 800A can have a generally matching cross-sectional profile. Insome embodiments, as illustrated in FIG. 21B, the modified broach 800Ahas a generally triangular cross-sectional profile. The modified broach800A can have a lumen or channel 802A extending along its entirelongitudinal length and sized and shaped so that the modified broach800A can be placed over a guide pin. The distal end 804A of the modifiedbroach 800A can be tapered and have a plurality of cutting surfaces 806Athat function to chisel away bone from the bore. The cutting surfaces806A can be angled slightly towards the distal end 804A with the moreproximal cutting surfaces 806A larger than the more distal cuttingsurfaces 806A. In some embodiments, the cutting surfaces 806A areoriented with each apex of the modified broach 800A. This configurationallows the modified broach 800A to progressively chisel away bone as themodified broach 800A is inserted into the bore. In some embodiments, themodified broach can also include one or more channels 808A that extendlongitudinally along the sides of the modified broach 800A that aid inthe removal of bone fragments from the bore. The channels 808A can belocated along the center of each face of the modified broach 800A, andcan have a curved surface or be formed from two or more flat surfaces.

In some embodiments as illustrated in FIGS. 21A and 21B, the modifiedbroach 800A can have additional cutting surfaces 810A located at eachapex of the modified broach 800A. In some embodiments, the additionalcutting surfaces 810A can be located on one or more of the apices of themodified broach 800A. In some embodiments, the additional cuttingsurfaces 810A can be located on each of the faces of the modified broach800A, such as where the channels 808A are shown in FIGS. 21A and 21B. Insome embodiments as illustrated in FIGS. 21C-21E, the additional cuttingsurfaces 810A, which can be circular, rectangular, triangular or anyother suitable shape, can be located on one or more of the faces of themodified broach 800A. In some embodiments, the additional cuttingsurfaces 810A can be located in a combination of one or more of theapices and faces of the modified broach 800A. The additional cuttingsurfaces 810A can be angled slightly distally so that the cuttingsurfaces can chisel away bone fragments as the modified broach 800A isadvanced into the bore. As described above, the additional cuttingsurfaces 810A can have circular shaped cutting surfaces or be any othershape, such as triangular, square, rectilinear, oval and the like. Thechannels can be sized to have a width or diameter of about 0.1 to 0.5the width of a face or side of the bore.

The additional cutting surfaces 810A can cut tubes or channels from theshaped bore that can be filled bone graft material and/or a biologicaid. In some embodiments, the drilled bore can be enlarged using themodified broach 800A to shape the bore into a general shape that matchesthe implant while also cutting out bone graft channels that extendbeyond the general implant profile. In some embodiments, the bone graftchannels can be located at the apexes of the shaped bore.

In some embodiments, a standard broach can be used to shape the borewhile additional tubes or channels can be made separately with a drilland specialized drill bit or drill fixture. In some embodiments, astandard broach can be used to initially shape the bore while a secondbroach can be used to cut out the additional tubes or channels.

As described above, the implant can be inserted into the shaped borewhile bone graft material and/or a biologic aid can be inserted into theadditional cut tubes or channels. In some embodiments, the bone graftmaterial and/or biologic aids can be formed into solid rods, with shapesmatching the cut tubes or channels, which can be impacted into each cuttube or channel. In other embodiments, the bone graft material and/orbiologic aids can be injected with a specialized syringe or otherinjection device into each of the cut tubes or channels. In someembodiments, the bone graft material and/or biologic aids can also besmeared or coated onto the implant either before or as the implant ininserted into the shaped bore.

The bone graft materials can be a liquid, gel, slurry, paste, powder,solid structure, matrix of granular material or other form, and caninclude a biologic aid that can promote and/or enhance bony ingrowth,tissue repair, and/or reduce inflammation, infection and pain. Forexample, the bone graft materials and/or biologic aid can include growthfactors, such as bone morphogenetic proteins (BMPs), hydroxyapatite in,for example, a liquid or slurry carrier, demineralized bone, morselizedautograft or allograft bone, bone fragments, medications to reduceinflammation, infection or pain such as analgesics, antibiotics andsteroids. In addition, a blood pellet formed by centrifugation of thepatient's blood, for example, can be included in the bone graftmaterials. In some embodiments, the blood pellet can be added in pelletform to the bone graft materials, while in other embodiments, the bloodpellet can be disassociated and mixed or incorporated with other bonegraft materials and/or biologic aids. In some embodiments, the growthfactors can be human recombinant growth factors, such as hr-BMP-2 and/orhr-BMP-7, or any other human recombinant form of BMP, for example. Thecarrier for the biologic aid can be a liquid or gel such as saline or acollagen gel, for example. The biologic aid can also be encapsulated orincorporated in a controlled released formulation so that the biologicaid is released to the patient at the implant site over a longerduration. For example, the controlled release formulation can beconfigured to release the biologic aid over the course of days or weeksor months, and can be configured to release the biologic aid over theestimated time it would take for the implant site to heal. The amount ofbiologic aid delivered to the implant structure can be controlled usinga variety of techniques, such as controlling or varying the amount ofcoating material applied to the implant and/or controlling or varyingthe amount of biologic aid incorporated into the coating material. Insome embodiments, in may be important to control the amount of biologicaid delivered because excessive use of certain biologic aids can resultin negative effects such as radicular pain, for example.

In some embodiments, the filling of the cutting tubes or channels withbone graft material at the apices around the implant helps reducehaloing artifacts around the implant. As shown in FIG. 26 , haloingrefers to CT imaging artifacts 1300A that generally occur around cornersof the implant 20A which can cause confusion in interpreting the CTimage. Replacing the relatively sharp corners and apices with circularchannels or tube can help to reduce the haloing artifacts.

FIGS. 22A and 22B illustrate a broach 900A without the additionalcutting surfaces for cutting out additional tubes or channels. Thebroach 900A can have a cross-sectional profile that generally matchesthe shape of the implant. For example, for a triangular shaped implant,the broach 900A can have a generally triangular shaped cross-sectionalprofile, as illustrated in FIGS. 22A and 22B. Likewise, for an implantwith a rectangular, square, or any other rectilinear shape, the broachcan have a generally matching cross-sectional profile. The broach 900Acan have a lumen or channel 902A extending along its entire longitudinallength and sized and shaped so that the broach 900A can be placed over aguide pin. The distal end 904A of the broach 900A can be tapered andhave a plurality of cutting surfaces 906A that function to chisel awaybone from the bore. The cutting surfaces 906A can be angled slightlytowards the distal end 904A with the more proximal cutting surfaces 906Alarger than the more distal cutting surfaces 906A. In some embodiments,the cutting surfaces 906A are oriented with each apex of the broach900A. This configuration allows the broach 900A to progressively chiselaway bone as the broach 900A is inserted into the bore. In someembodiments, the broach 900A can also include one or more channels 908Athat extend longitudinally along the sides of the broach 900A that aidin the removal of bone fragments from the bore. The channels 908A can belocated along the center of each face of the broach 900A, and can have acurved surface or be formed from two or more flat surfaces. In someembodiments, the distal face 905A of the distal end 904A can be flat orblunt and be shaped generally like a ring with cutouts along theperimeter for the channels 908A.

FIGS. 23A and 23B illustrate another embodiment of a broach 1000A with asimilar design to the broach illustrated in FIGS. 22A and 22B, exceptthat the broach 1000A illustrated in FIGS. 23A and 23B has a distal end1004A that tapers into a pointed or bullet shaped tip rather than a flatsurface. Like the broach 900A illustrated in FIGS. 22A and 22B, thebroach 1000A illustrated in FIGS. 23A and 23B can have a cross-sectionalprofile that generally matches the shape of the implant. For example,for a triangular shaped implant, the broach 1000A can have a generallytriangular shaped cross-sectional profile, as illustrated in FIGS. 23Aand 23B. Likewise, for an implant with a rectangular, square, or anyother rectilinear shape, the broach can have a generally matchingcross-sectional profile. The broach 1000A can have a lumen or channel1002A extending along its entire longitudinal length and sized andshaped so that the broach 1000A can be placed over a guide pin. Thedistal end 1004A of the broach 1000A can be tapered and have a pluralityof cutting surfaces 1006A that function to chisel away bone from thebore. The cutting surfaces 1006A can be angled slightly towards thedistal end 1004A with the more proximal cutting surfaces 1006A largerthan the more distal cutting surfaces 1006A. In some embodiments, thecutting surfaces 1006A are oriented with each apex of the broach 1000A.This configuration allows the broach 1000A to progressively chisel awaybone as the broach 1000A is inserted into the bore. In some embodiments,the broach 1000A can also include one or more channels 1008A that extendlongitudinally along the sides of the broach 1000A that aid in theremoval of bone fragments from the bore. The channels 1008A can belocated along the center of each face of the broach 1000A, and can havea curved surface or be formed from two or more flat surfaces. Theproximal portion of the broach shaft 1010A can have markings 1012A thatcan provide indicators to the operator regarding the depth ofpenetration of the broach 1000A into the bone. The markings 1012A can bea transverse line and can include numerical indications of penetrationdepth.

However, in contrast to the embodiment of the broach illustrated inFIGS. 22A and 22B, the embodiment of the broach 1000A illustrated inFIGS. 23A and 23B has a pointed tip 1005A with a diameter at the distalend that is equal to the diameter of the lumen or channel 1002A, and thediameter of the pointed tip 1005A can gradually increase in the proximaldirection. The pointed tip 1005A can comprise a plurality of beveledfaces 1009A angled towards the distal end 1004A. The distal portion ofthe pointed tip 1005A can be formed into a smooth tapering surface 1007Athat narrows until it reaches the lumen or channel 1002A at the distalend 1004A. The smooth tapering surface 1007A can act as a cuttingsurface around the opening of the lumen 1002A to remove bone around theguide pin. As the broach 1000A traverses over the guide pin and isforced into the bone, the pointed tip 1005A can penetrate into the bonearound the guide pin until the cutting surfaces 1006A can engage andchisel away the bone around the guide pin. Such a design can reduce oreliminate the need for additional drilling after the guide pin is placein the bone. The broach 1000A can be simply placed over the guide pin toform the bore into the bone without the need of placing a drill bit overthe guide pin and drilling a bore and then using the broach to shape thecircular bore into a triangular or rectilinear bore.

FIGS. 24A and 24B illustrate another embodiment of a broach 1100A with asimilar design to the broach illustrated in FIGS. 22A and 22B, exceptthat the broach 1100A illustrated in FIGS. 24A and 24B has a distal end1104A with an additional distal cutting surface 1103A adjacent to andsurrounding the opening of the lumen or channel 1102A that forms themost distal part of the broach 1100A. Like the broach 900A illustratedin FIGS. 22A and 22B, the broach 1100A illustrated in FIGS. 24A and 24Bcan have a cross-sectional profile that generally matches the shape ofthe implant. For example, for a triangular shaped implant, the broach1100A can have a generally triangular shaped cross-sectional profile, asillustrated in FIGS. 24A and 24B. Likewise, for an implant with arectangular, square, or any other rectilinear shape, the broach can havea generally matching cross-sectional profile. The broach 1100A can havea lumen or channel 1102A extending along its entire longitudinal lengthand sized and shaped so that the broach 1100A can be placed over a guidepin. The distal end 1104A of the broach 1100A can be tapered and have aplurality of cutting surfaces 1106A that function to chisel away bonefrom the bore. The cutting surfaces 1106A can be angled slightly towardsthe distal end 1104A with the more proximal cutting surfaces 1106Alarger than the more distal cutting surfaces 1106A. In some embodiments,the cutting surfaces 1106A are oriented with each apex of the broach1100A. This configuration allows the broach 1100A to progressivelychisel away bone as the broach 1100A is inserted into the bore. In someembodiments, the broach 1100A can also include one or more channels1108A that extend longitudinally along the sides of the broach 1100Athat aid in the removal of bone fragments from the bore. The channels1108A can be located along the center of each face of the broach 1100A,and can have a curved surface or be formed from two or more flatsurfaces. The proximal portion of the broach shaft 1110A can havemarkings 1112A that can provide indicators to the operator regarding thedepth of penetration of the broach 1100A into the bone. The markings1112A can be a transverse line and can include numerical indications ofpenetration depth.

However, as discussed briefly above, in contrast to the embodiment ofthe broach illustrated in FIGS. 22A and 22B, the embodiment of thebroach 1100A illustrated in FIGS. 24A and 24B has a distal end 1104Awith an additional distal cutting surface 1103A adjacent to andsurrounding the opening of the lumen or channel 1102A that forms themost distal part of the broach 1100A. As the broach 1100A traverses overthe guide pin and is forced into the bone, the distal cutting surface1103A engages the bone around the guide pin and begins cutting,chiseling and removing the bone from around the guide pin, therebystarting the bore to receive the implant. As the broach 1100A penetratesfurther into the bone, the primary cutting surfaces 1106A can engage andchisel away additional bone around the guide pin, thereby enlarging thebore. Such a design can reduce or eliminate the need for additionaldrilling after the guide pin is place in the bone. The broach 1100A canbe simply placed over the guide pin to form the bore into the bonewithout the need of placing a drill bit over the guide pin and drillinga bore and then using the broach to shape the circular bore into atriangular or rectilinear bore.

FIGS. 25A and 25B illustrate another embodiment of a broach 1200A havinga pyramid shaped tip 1204A. Like the broach 900A illustrated in FIGS.22A and 22B, the broach 1200A illustrated in FIGS. 25A and 25B can havea cross-sectional profile that generally matches the shape of theimplant. For example, for a triangular shaped implant, the broach 1200Acan have a generally triangular shaped cross-sectional profile, asillustrated in FIGS. 25A and 25B. Likewise, for an implant with arectangular, square, or any other rectilinear shape, the broach can havea generally matching cross-sectional profile. In some embodiments, thebroach 1200A can have a lumen or channel 1202A extending along itsentire longitudinal length and sized and shaped so that the broach 1200Acan be placed over a guide pin.

The pyramid shaped tip 1204A can comprise three faces 1206A that tapertowards the distal end of the broach 1200A. At the distal end of thebroach 1200A can be an opening to the lumen 1202A. Surround the openingcan be a plurality of cutting surfaces 1208A, 1209A located at both theapices between the faces 1206A and along the distal end of each face1206A between the apices. The cutting surfaces 1208A, 1209A areconfigured to cut and chisel out the bone around the guide pin to formthe bore for the implant. Furthermore, the cutting surfaces 1208 locatedat the apices can be arranged to form teeth with a pointed tip that canpenetrate into and cut and chisel the bone surrounding the guide pin.

Implants for Facet Fusion

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention that may be embodied inother specific structure. While the preferred embodiment has beendescribed, the details may be changed without departing from theinvention, which is defined by the claims.

I. The Implant Structure

FIG. 30 shows a representative embodiment of an elongated, stem-like,cannulated implant structure 20B. As will be described in greater detaillater, the implant structure 20B is sized and configured for thefixation of bones which are to be fused (arthrodesed) (i.e. fixation oftwo or more individual bones that are adjacent and/or jointed) and/orthe stabilization of adjacent bone structures. In particular, and aswill be demonstrated, the implant structure is well suited for thefusion or stabilization of adjacent bone structures in the lumbar regionof the spine, either across the intervertebral disc or across one ormore facet joints.

The implant structure 20B can be formed—e.g., by machining, molding, orextrusion—from a durable material usable in the prosthetic arts that isnot subject to significant bio-absorption or resorption by surroundingbone or tissue over time. The implant structure 20B, is intended toremain in place for a time sufficient to stabilize a bone fracture orfusion site. Such materials include, but are not limited to, titanium,titanium alloys, tantalum, tivanium (aluminum, vanadium, and titanium),chrome cobalt, surgical steel, or any other total joint replacementmetal and/or ceramic, sintered glass, artificial bone, any uncementedmetal or ceramic surface, or a combination thereof.

Alternatively, the implant structure 20B may be formed from a suitabledurable biologic material or a combination of metal and biologicmaterial, such as a biocompatible bone-filling material. The implantstructure 20B may be molded from a flowable biologic material, e.g.,acrylic bone cement, that is cured, e.g., by UV light, to a non-flowableor solid material.

The implant structure 20B is sized according to the local anatomy. Themorphology of the local structures can be generally understood bymedical professionals using textbooks of human skeletal anatomy alongwith their knowledge of the site and its disease or injury. Thephysician is also able to ascertain the dimensions of the implantstructure 20B based upon prior analysis of the morphology of thetargeted bone region using, for example, plain film x-ray, fluoroscopicx-ray, or MRI or CT scanning.

As FIGS. 31 to 34 show, the implant structure 20B can take variousshapes and have various cross-sectional geometries. The implantstructure 20B can have, e.g., a generally curvilinear (i.e., round oroval) cross-section—as FIG. 31 shows for purposes of illustration—or agenerally rectilinear cross section (i.e., square or rectangular orhexagon or H-shaped or triangular—as FIG. 32 shows for purposes ofillustration—or combinations thereof. In FIG. 30 , the implant structure20B is shown to be triangular in cross section, which effectivelyresists rotation and micromotion once implanted.

As FIGS. 33 and 34 show, the implant structure 20B, whether curvilinear(FIG. 33 ) or rectilinear (FIG. 34 ) can include a tapered region 34B atleast along a portion of its axial length, meaning that the width ordiameter of the implant structure 20B incrementally increases along itsaxial length. Desirably, the tapered region 34B corresponds with, inuse, the proximal region of the implant structure 20B (i.e., the lastpart of the implant structure 20B to enter bone). The amount of theincremental increase in width or diameter can vary. As an example, foran implant structure 20B having a normal diameter of 7 mm, the magnitudeof the incremental increase at its maximum can range between about 0.25mm to 1.25 mm. The tapered region 34 enhances the creation andmaintenance of compression between bone segments or regions.

As FIG. 30 shows, the implant structure 20B includes a region 24B formedalong at least a portion of its length to promote bony in-growth onto orinto surface of the structure and/or bony growth entirely through all ora portion of the structure. The bony in-growth or through-growth region24B along the surface of the implant structure 20B accelerates bonyin-growth or through-growth onto, into, or through the implant structure20B. Bony in-growth or through-growth onto, into, or through the implantstructure 20B helps speed up the fusion process of the adjacent boneregions fixated by the implant structure 20B.

The bony in-growth or through-growth region 24B desirably extends alongthe entire outer surface of the implant structure 20B, as shown in FIGS.30 to 34 . The bony in-growth region 24B or through-growth can comprise,e.g., through holes, and/or various surface patterns, and/or varioussurface textures, and/or pores, or combinations thereof. Theconfiguration of the bony in-growth or through-growth region 24B can, ofcourse, vary. By way of examples, the bony in-growth or through-growthregion 24B can comprise an open mesh configuration; or beadedconfiguration; or a trabecular configuration; or include holes orfenestrations. Any configuration conducive to bony in-growth and/or bonythrough-growth will suffice.

The bony in-growth or through-growth region 24B can be coated or wrappedor surfaced treated to provide the bony in-growth or through-growthregion, or it can be formed from a material that itself inherentlypossesses a structure conducive to bony in-growth or through-growth,such as a porous mesh, hydroxyapatite, or other porous surface. The bonyin-growth or through-growth region can includes holes that allow bone togrow throughout the region.

In a preferred embodiment, the bony in-growth region or through-growthregion 24B comprises a porous plasma spray coating on the implantstructure 20B. This creates a biomechanically rigorous fixation/fusionsystem, designed to support reliable fixation/fusion and acute weightbearing capacity.

The bony in-growth or through-growth region 24B may further be coveredwith various other coatings such as antimicrobial, antithrombotic, andosteoinductive agents, or a combination thereof. The entire implantstructure 20B may be impregnated with such agents, if desired.

The implant structure includes an interior bore that accommodates itsplacement in a non-invasive manner by sliding over a guide pin, as willbe described in greater detail later.

As before stated, the implant structure 20B is well suited for thefusion and/or stabilization of adjacent bone structures in the lumbarregion of the spine. Representative examples of the placement of theimplant structure 20B in the lumbar region of the spine will now bedescribed.

A. Use of the Implant Structures to Achieve Anterior Lumbar InterbodyFusion

FIG. 35 shows, in an exploded view prior to implantation, arepresentative configuration of an assembly of one or more implantstructures 20B sized and configured to achieve anterior lumbar interbodyfusion, in a non-invasive manner and without removal of theintervertebral disc. FIGS. 36 to 38 show the assembly afterimplantation, respectively, in an anterior view, a right lateral view,and a superior left lateral perspective view.

In the representative embodiment illustrated in FIGS. 36 to 38 , theassembly comprises three implant structures 20B. It should beappreciated, however, that a given assembly can include a greater orlesser number of implant structures 20B.

In the representative embodiment shown in FIGS. 36 to 38 , the threeimplant structures 20B are spaced in an adjacent lateral array. Theimplant structures 20B extend from an anterolateral region of a selectedvertebral body (i.e., a lateral region anterior to a transverseprocess), across the intervertebral disc into an opposite anterolateralregion of an adjacent caudal (inferior) vertebra. As shown in FIGS. 36to 38 , the array of implant structures 20B extends in an angled path(e.g., about 20.degree. to about 40.degree. off horizontal) through thecranial (superior) lumbar vertebral body (shown as L4) in an inferiordirection, through the adjoining intervertebral disc, and terminates inthe next adjacent caudal (inferior) lumbar vertebral body (shown as L5).

More particularly, in the representative embodiment shown in FIGS. 35 to38 , the implant structures 20B enter the right anterolateral region ofvertebra L4 and terminate within the left anterolateral interior ofvertebra L5, spanning the intervertebral disc between L4 and L5.

Alternatively, or in combination, an array of implant structures 20B canlikewise extend between L5 and S1 in the same trans-disc formation.

The implant structures 20B are sized according to the local anatomy. Theimplant structures 20B can be sized differently, e.g., 3 mm, 4 mm, 6 mm,etc.), to accommodate anterolateral variations in the anatomy. Theimplant structures 20B can be sized for implantation in adults orchildren.

The intimate contact created between the bony in-growth orthrough-growth region 24B along the surface of the implant structure 20Baccelerates bony in-growth or through-growth onto, into, or through theimplant structure 20B, to accelerate trans-disc fusion between theselumbar vertebrae.

FIGS. 39A to 39G diagrammatically show, for purposes of illustration, arepresentative lateral (or posterolateral) procedure for implanting theassembly of implant structures 20B shown in FIGS. 36 to 38 .

The physician identifies the vertebrae of the lumbar spine region thatare to be fused using, e.g., the Faber Test, or CT-guided injection, orX-ray/MRI of the lumbar spine. Aided by lateral and anterior-posterior(A-P) c-arms, and with the patient lying in a prone position (on theirstomach), the physician makes a 3 mm incision laterally orposterolaterally from the side (see FIG. 39A). Aided by conventionalvisualization techniques, e.g., using X-ray image intensifiers such as aC-arms or fluoroscopes to produce a live image feed which is displayedon a TV screen, a guide pin 38B is introduced by conventional means intoL4 (see FIG. 39B) for the first, most anterolateral implant structure(closest to the right transverse process of L4), in the desired angledinferiorly-directed path through the intervertebral disc and into theinterior left anterolateral region of vertebra L5.

When the guide pin 38B is placed in the desired orientation, thephysician desirable slides a soft tissue protector over the guide pin38B before proceeding further. To simplify the illustration, the softtissue protector is not shown in the drawings.

Through the soft tissue protector, a cannulated drill bit 40B is nextpassed over the guide pin 38B (see FIG. 39C). The cannulated drill bit40B forms a pilot insertion path or bore 42B along the first angled pathdefined by the guide pin 38B. A single drill bit or multiple drill bits40B can be employed to drill through bone fragments or bone surfaces tocreate a pilot bore 42B of the desired size and configuration.

When the pilot bore 42B is completed, the cannulated drill bit 40B iswithdrawn over the guide pin 38B.

Through the soft tissue protector, a broach 44B having the externalgeometry and dimensions matching the external geometry and dimensions ofthe implant structure 20B (which, in the illustrated embodiment, istriangular) (see FIG. 39D) is tapped through the soft tissue protectorover the guide pin 38B and into the pilot bore 42B. The shaped broach44B cuts along the edges of the pilot bore 42B to form the desiredprofile (which, in the illustrated embodiment, is triangular) toaccommodate the implant structure 20B.

The broach 44B is withdrawn (see FIG. 39E), and the first, mostanterolateral implant structure 20B is passed over the guide pin 38Bthrough the soft tissue protector into the broached bore 48B. The guidepin 38B and soft tissue protector are withdrawn from the first implantstructure 20B.

The physician repeats the above-described procedure sequentially for thenext anterolateral implant structures 20B: for each implant structure,inserting the guide pin 38B, forming the pilot bore, forming thebroached bore, inserting the respective implant structure, withdrawingthe guide pin, and then repeating the procedure for the next implantstructure, and so on until all implant structures 20B are placed (asFIGS. 39F and 39G indicate). The incision site(s) are closed.

In summary, the method for implanting the assembly of the implantstructures 20B comprises (i) identifying the bone structures to be fusedand/or stabilized; (ii) opening an incision; (iii) using a guide pin toestablished a desired implantation path through bone for the implantstructure 20B; (iv) guided by the guide pin, increasing the crosssection of the path; (v) guided by the guide pin, shaping the crosssection of the path to correspond with the cross section of the implantstructure 20B; (vi) inserting the implant structure 20B through the pathover the guide pin; (vii) withdrawing the guide pin; (viii) repeating,as necessary, the procedure sequentially for the next implantstructure(s) until all implant structures 20B contemplated areimplanted; and (ix) closing the incision.

As FIGS. 40 and 41 show, assemblies comprising one or more implantstructures 20B can be inserted from left and/or right anterolateralregions of a given lumbar vertebra, in an angled path through theintervertebral disc and into an opposite anterolateral interior regionof the next inferior lumbar vertebra.

For purposes of illustration, FIG. 40 shows two implant structures 20Bentering on the right anterolateral side of L4, through theintervertebral disc and into the left anterolateral region of L5, andone implant structure 20B entering on the left anterolateral side of L4,through the intervertebral disc and into the right anterolateral regionof L5. In this arrangement, the left and right implant structures 20Bcross each other in transit through the intervertebral disc.

As another illustration of a representative embodiment, FIG. 41 showsone implant structure 20B entering on the right anterolateral side ofL4, through the intervertebral disc and into the left anterolateralregion of L5, and one implant structure 20B entering on the leftanterolateral side of L4, through the intervertebral disc and into theright anterolateral region of L5. In this arrangement as well, the leftand right implant structures 20B cross each other in transit through theintervertebral disc.

B. Use of Implant Structures to Achieve Translaminar Lumbar Fusion(Posterior Approach)

FIG. 42 shows, in an exploded view prior to implantation, arepresentative configuration of an assembly of one or more implantstructures 20B sized and configured to achieve translaminar lumbarfusion in a non-invasive manner and without removal of theintervertebral disc. FIG. 43 shows the assembly after implantation,respectively, in an inferior transverse plane view. The implantstructures illustrated in FIGS. 47-49 can also be used to achievetranslaminar lumbar fusion as described herein.

As can be seen in the representative embodiment illustrated in FIGS. 42and 43 , the assembly comprises two implant structures 20B. The firstimplant structure 20B extends from the left superior articular processof vertebra L5, through the adjoining facet capsule into the leftinferior articular process of vertebra L4, and, from there, furtherthrough the lamina of vertebra L4 into an interior right posterolateralregion of vertebra L4 adjacent the spinous process. The second implantstructure 20B extends from the right superior articular process ofvertebra L5, through the adjoining facet capsule into the right inferiorarticular process of vertebra L4, and, from there, further through thelamina of vertebra L4 into an interior left posterolateral region ofvertebra L4 adjacent the spinous process. The first and second implantstructures 20B cross each other within the medial lamina of vertebra L4.

The first and second implant structures 20B are sized and configuredaccording to the local anatomy. The selection of a translaminar lumbarfusion (posterior approach) is indicated when the facet joints arealigned with the sagittal plane. Removal of the intervertebral disc isnot required, unless the condition of the disc warrants its removal.

A procedure incorporating the technical features of the procedure shownin FIGS. 39A to 39G can be tailored to a posterior procedure forimplanting the assembly of implant structures 20B shown in FIGS. 42 and43 . The method comprises (i) identifying the vertebrae of the lumbarspine region that are to be fused; (ii) opening an incision, whichcomprises, e.g., with the patient lying in a prone position (on theirstomach), making a 3 mm posterior incision; and (iii) using a guide pinto established a desired implantation path through bone for the first(e.g., left side) implant structure 20B, which, in FIGS. 42 and 43 ,traverses through the left superior articular process of vertebra L5,through the adjoining facet capsule into the left inferior articularprocess of vertebra L4, and then through the lamina of vertebra L4 intoan interior right posterolateral region of vertebra L4 adjacent thespinous process. The method further includes (iv) guided by the guidepin, increasing the cross section of the path; (v) guided by the guidepin, shaping the cross section of the path to correspond with the crosssection of the implant structure; (vi) inserting the implant structure20B through the path over the guide pin; (vii) withdrawing the guidepin; and (viii) using a guide pin to established a desired implantationpath through bone for the second (e.g., right side) implant structure20B, which, in FIGS. 42 and 43 , traverses through the right superiorarticular process of vertebra L5, through the adjoining facet capsuleinto the right inferior articular process of vertebra L4, and throughthe lamina of vertebra L4 into an interior left posterolateral region ofvertebra L4 adjacent the spinous process. The physician repeats theremainder of the above-described procedure sequentially for the rightimplant structure 20B as for the left, and, after withdrawing the guidepin, closes the incision.

The intimate contact created between the bony in-growth orthrough-growth region 24B along the surface of the implant structure 20Bacross the facet joint accelerates bony in-growth or through-growthonto, into, or through the implant structure 20B, to accelerate fusionof the facets joints between L4 and L5. Of course, translaminar lumbarfusion between L5 and S1 can be achieved using first and second implantstructures in the same manner.

C. Use of Implant Structures to Achieve Lumbar Facet Fusion (PosteriorApproach)

FIG. 44 shows, in an exploded view prior to implantation, arepresentative configuration of an assembly of one or more implantstructures 20B sized and configured to lumbar facet fusion, in anon-invasive manner and without removal of the intervertebral disc.FIGS. 45 and 46 show the assembly after implantation, respectively, inan inferior transverse plane view and a lateral view. The implantstructures illustrated in FIGS. 47-49 can also be used to achieve lumbarfacet fusion as described herein.

As can be seen in the representative embodiment illustrated in FIGS. 44and 46 , the assembly comprises two implant structures 20B. The firstimplant structure 20B extends from the left inferior articular processof vertebra L4, through the adjoining facet capsule into the leftsuperior articular process of vertebra L5 and into the pedicle ofvertebra L5. The second implant structure 20B extends from the rightinferior articular process of vertebra L5, through the adjoining facetcapsule into the right superior articular process of vertebra L5 andinto the pedicle of vertebra L5. In this arrangement, the first andsecond implant structures 20B extend in parallel directions on the leftand right pedicles of vertebra L5. The first and second implantstructures 20B are sized and configured according to the local anatomy.The selection of lumbar facet fusion (posterior approach) is indicatedwhen the facet joints are coronally angled. Removal of theintervertebral disc is not necessary, unless the condition of the discwarrants its removal.

A procedure incorporating the technical features of the procedure shownin FIGS. 39A to 39G can be tailored to a posterior procedure forimplanting the assembly of implant structures 20B shown in FIGS. 44 to46 . The method comprises (i) identifying the vertebrae of the lumbarspine region that are to be fused; (ii) opening an incision, whichcomprises, e.g., with the patient lying in a prone position (on theirstomach), making a 3 mm posterior incision; and (iii) using a guide pinto established a desired implantation path through bone for the first(e.g., left side) implant structure 20B, which, in FIGS. 44 to 46 ,traverses through the left inferior articular process of vertebra L4,through the adjoining facet capsule into the left superior articularprocess of vertebra L5 and into the pedicle of vertebra L5. The methodfurther includes (iv) guided by the guide pin, increasing the crosssection of the path; (v) guided by the guide pin, shaping the crosssection of the path to correspond with the cross section of the implantstructure 20B; (vi) inserting the implant structure 20B through the pathover the guide pin; (vii) withdrawing the guide pin; and (viii) using aguide pin to established a desired implantation path through bone forthe second (e.g., right side) implant structure 20B, which, in FIGS. 44to 46 , traverses through the right inferior articular process ofvertebra L5, through the adjoining facet capsule into the right superiorarticular process of vertebra L5 and into the pedicle of vertebra L5.The physician repeats the remainder of the above-described proceduresequentially for the right implant structure 20B as for the left and,withdrawing the guide pin, closes the incision.

The intimate contact created between the bony in-growth orthrough-growth region 24B along the surface of the implant structure 20Bacross the facet joint accelerates bony in-growth or through-growthonto, into, or through the implant structure 20B, to accelerate fusionof the facets joints between L4 and L5.

Of course, translaminar lumbar fusion between L5 and S1 can be achievedusing first and second implant structures in the same manner.

FIG. 47 illustrates another embodiment of an implant structure 2100Bwhich has a rectilinear cross-section and a curved elongate body 2102Bhaving a lumen 2104B for receiving a guide wire or guide pin. In someembodiments, the curved elongate body 212B can have a constant curvaturewhich can be particularly suited to facilitate insertion of a curved andrigid implant structure 210B into a curved bore or channel also with amatching constant curvature. In this context, constant curvature refers,for example, to a curvature of a circle or spiral. Although the implantstructure 2100B is shown as having a rectilinear cross-section, andspecifically a triangular cross-section, other rectilinearcross-sections are contemplated, include square, rectangular, rhomboid,trapezoidal, pentagonal, hexagonal and the like. In addition, theimplant structure 2100B can alternatively have a curvilinearcross-section, such as circular, elliptical, oval, oblong, and the like.The primary new feature disclosed in FIG. 47 over the other embodimentsof the implant structure described herein is the curved elongate body2102B which can be implemented in any of the implanted structuresdisclosed and/or contemplated herein. In some embodiments, the implantstructure can be made of a shape memory material, such as a nickeltitanium alloy, that can adopt a predetermined curved configurationduring and/or after implantation. In some embodiments, implantstructures made of a shape memory material can have an initial deliveryconfiguration that is straight, partially curved or curved, where thecurvature can either be constant or variable.

FIG. 48 illustrates another embodiment of an implant structure 2200Bwhich has a rectilinear cross-section and an elongate body 2202B thatcan be made from a plurality of interlocking segments 2204B that allowsthe elongate body 2202B to bend and take on a variety of differentconfigurations, from straight to curved with a constant curvature tocurved with a variable curvature. The elongate body 2202B can also havea lumen 2204B for receiving a guidewire or guide pin. In someembodiments, the implant structure 2200B can be flexible and/or formedin-situ. In some embodiments, the implant structure can be made of ashape memory material, such as a nickel titanium alloy, that can adopt apredetermined curved configuration during and/or after implantation.

FIG. 49 illustrates another embodiment of a curved implant structure2300B that can be formed in-situ. The implant structure 2300B can beinflatable and can be filled with a curable polymer or resin or cement.The walls 2302B of the implant structure 2300B can be made of either aninelastic material that cannot stretch or an elastic material that canstretch. The implant structure 2300B can be delivered in a collapsed anduninflated state over a guidewire, and can then be filled with thecurable material through, for example, a valve 2304B located on theproximal end of the implant structure 2300B. In the inflatedconfiguration, the implant structure 2300B can take any of theconfigurations disclosed herein, such as having a rectilinearcross-section or a curvilinear cross-section and having a curvedconfiguration or a straight configuration. The implant structure canhave an elongate body with a lumen 2306B for receiving a guidewire orguide pin.

In some embodiments, the curved implant structures illustrated in FIGS.47-49 can be used in one of the facet fusion procedures as shown anddescribed, for example, above in reference to FIGS. 42-46 . FIGS. 50-54illustrate the same procedures as FIGS. 42-46 expect that a curvedimplant structure is used in place of a straight implant structure. Insome embodiments, the transfacet fusion procedure, as illustrated inFIGS. 44-46 , involves placing the implant structures such that theimplant structures do not cross the spinal process. In contrast,translaminar facet fusion procedures generally involve placing theimplant structures such that the implant structures cross the spinalprocess, as illustrated in FIGS. 42 and 43 . The curved implantstructure can provide improved transfacet fusion and translaminar facetfusion over a straight implant structure by curving around sensitivenerve tissue which can provide a larger safety margin and can allow alonger implant structure to be used. More generally, the curved implantstructures can be advantageously used in any of the bone fusion orfixation procedures described herein, especially where a curved geometryis useful for maintaining the implant structure within bone tissue whileavoiding sensitive tissues such as nerve tissue. The surfaces of thecurved implant structures can be porous and/or textured and can betreated and/or coated with bone growth promoting materials or compounds,such as hydroxyapatite and bone morphogenetic proteins (BMPs).

To form the curved bore or channel a curved through bone such as thevertebrae, a curved guidewire or guide pin can be inserted into the boneby, for example, placing the curved guidewire or guide pin against thebone surface and rotating the curved guidewire or guide pin about anaxis. Alternatively or in addition to the curved guidewire or guide pin,a steerable drill or cutting device can be used to create the bore or apilot bore. In some embodiments, the steerable drill or cutting devicecan be advanced over, through or with a curved guide track or sheath toform the curved bore. In some embodiments, the drill bit or cuttingdevice can be curved and can form the curved bore by placing the drillbit or cutting device against the bone surface and rotating the drillbit or cutting device about an axis. In some embodiments, the drill bitor cutting device can have a guidewire lumen that allows the drill bitor cutting device to be advanced over the curved guidewire. Similarly, acurved broach can be used to shape the curved bore into anycross-sectional shape described herein, such as rectilinear andtriangular, in particular. In some embodiments, the curved broach canhave a guidewire lumen that allows the curved broach to be advanced overthe curved guidewire. In some embodiments, the curved broach can berotated about an axis like the guidewire and cutting device.

Once the curved bore is formed, the implant structure can be inserted asdescribed above. In some embodiments, the bore can be formed in areverse fashion, by for example, creating a curved insertion path thatstarts in the lamina of the superior vertebra, extends distally andlaterally to the inferior articular process of the superior vertebra,through the joint between the superior vertebra and the inferiorvertebrae, and into the superior articular process of the inferiorvertebra. The curved bone fixation implant can be inserted through theinsertion path from the lamina of the superior vertebra, extendingdistally and laterally to the inferior articular process of the superiorvertebra, through the joint between the superior vertebra and theinferior vertebrae, and into the superior articular process of theinferior vertebra

II. Conclusion

The various representative embodiments of the assemblies of the implantstructures, as described, make possible the achievement of diverseinterventions involving the fusion and/or stabilization of lumbar andsacral vertebra in a non-invasive manner, with minimal incision, andwithout the necessitating the removing the intervertebral disc. Therepresentative lumbar spine interventions described can be performed onadults or children and include, but are not limited to, lumbar interbodyfusion; translaminar lumbar fusion; lumbar facet fusion; trans-iliaclumbar fusion; and the stabilization of a spondylolisthesis. It shouldbe appreciated that such interventions can be used in combination witheach other and in combination with conventional fusion/fixationtechniques to achieve the desired therapeutic objectives.

Significantly, the various assemblies of the implant structures asdescribed make possible lumbar interbody fusion without the necessity ofremoving the intervertebral disc. For example, in conventional anteriorlumbar interbody fusion procedures, the removal of the intervertebraldisc is a prerequisite of the procedure. However, when using theassemblies as described to achieve anterior lumbar interbody fusion,whether or not the intervertebral disc is removed depends upon thecondition of the disc, and is not a prerequisite of the procedureitself. If the disc is healthy and has not appreciably degenerated, oneor more implant structures can be individually inserted in a minimallyinvasive fashion, across the intervertebral disc in the lumbar spinearea, leaving the disc intact.

In all the representative interventions described, the removal of adisc, or the scraping of a disc, is at the physician's discretion, basedupon the condition of the disc itself, and is not dictated by theprocedure. The bony in-growth or through-growth regions of the implantstructures described provide both extra-articular and intra osseousfixation, when bone grows in and around the bony in-growth orthrough-growth regions.

Conventional tissue access tools, obturators, cannulas, and/or drillscan be used during their implantation. No disc preparation, removal ofbone or cartilage, or scraping are required before and during formationof the insertion path or insertion of the implant structures, so aminimally invasive insertion path sized approximately at or about themaximum outer diameter of the implant structures need be formed. Still,the implant structures, which include the elongated bony in-growth orthrough-growth regions, significantly increase the size of the fusionarea, from the relatively small surface area of a given joint betweenadjacent bones, to the surface area provided by an elongated bonyin-growth or through-growth regions. The implant structures can therebyincrease the surface area involved in the fusion and/or stabilization by3-fold to 4-fold, depending upon the joint involved.

The implant structures can obviate the need for autologous grafts, bonegraft material, additional pedicle screws and/or rods, hollow modularanchorage screws, cannulated compression screws, cages, or fixationscrews. Still, in the physician's discretion, bone graft material andother fixation instrumentation can be used in combination with theimplant structures.

The implant structures make possible surgical techniques that are lessinvasive than traditional open surgery with no extensive soft tissuestripping and no disc removal. The assemblies make possiblestraightforward surgical approaches that complement the minimallyinvasive surgical techniques. The profile and design of the implantstructures minimize rotation and micro-motion. Rigid implant structuresmade from titanium provide immediate post-op fusion stability. A bonyin-growth region comprising a porous plasma spray coating with irregularsurface supports stable bone fixation/fusion. The implant structures andsurgical approaches make possible the placement of larger fusion surfaceareas designed to maximize post-surgical weight bearing capacity andprovide a biomechanically rigorous implant designed specifically tostabilize the heavily loaded lumbar spine.

Systems and Methods for Removing an Implant

Elongated, stem-like implant structures 20C like that shown in FIG. 55make possible the fixation of the SI-Joint (shown in anterior andposterior views, respectively, in FIGS. 57 and 58 ) in a minimallyinvasive manner. These implant structures 20C can be effectivelyimplanted through the use a lateral surgical approach. The procedure isdesirably aided by conventional lateral, inlet, and outlet visualizationtechniques, e.g., using X-ray image intensifiers such as a C-arms orfluoroscopes to produce a live image feed, which is displayed on a TVscreen.

In one embodiment of a lateral approach (see FIGS. 59, 60, and 61A/B),one or more implant structures 20C are introduced laterally through theilium, the SI-Joint, and into the sacrum. This path and resultingplacement of the implant structures 20C are best shown in FIGS. 60 and61A/B. In the illustrated embodiment, three implant structures 20C areplaced in this manner. Also in the illustrated embodiment, the implantstructures 20C are rectilinear in cross section and triangular in thiscase, but it should be appreciated that implant structures 20C of otherrectilinear cross sections can be used.

Before undertaking a lateral implantation procedure, the physicianidentifies the SI-Joint segments that are to be fixated or fused(arthrodesed) using, e.g., the Fortin finger test, thigh thrust, FABER,Gaenslen's, compression, distraction, and diagnostic SI joint injection.

Aided by lateral, inlet, and outlet C-arm views, and with the patientlying in a prone position, the physician aligns the greater sciaticnotches and then the alae (using lateral visualization) to provide atrue lateral position. A 3 cm incision is made starting aligned with theposterior cortex of the sacral canal, followed by blunt tissueseparation to the ilium. From the lateral view, the guide pin 38C (withsleeve (not shown)) (e.g., a Steinmann Pin) is started resting on theilium at a position inferior to the sacrum end plate and just anteriorto the sacral canal. In the outlet view, the guide pin 38C should beparallel to the sacrum end plate at a shallow angle anterior (e.g.,15.degree. to 20.degree. off the floor, as FIG. 61A shows). In a lateralview, the guide pin 38C should be posterior to the sacrum anterior wall.In the outlet view, the guide pin 38C should be superior to the firstsacral foramen and lateral of mid-line. This corresponds generally tothe sequence shown diagrammatically in FIGS. 56A and 56B. A soft tissueprotector (not shown) is desirably slipped over the guide pin 38C andfirmly against the ilium before removing the guide pin sleeve (notshown).

Over the guide pin 38C (and through the soft tissue protector), thepilot bore 42C is drilled in the manner previously described, as isdiagrammatically shown in FIG. 56C. The pilot bore 42C extends throughthe ilium, through the SI-Joint, and into the S1. The drill bit 40C isremoved.

The shaped broach 44C is tapped into the pilot bore 42C over the guidepin 38C (and through the soft tissue protector) to create a broachedbore 48 with the desired profile for the implant structure 20C, which,in the illustrated embodiment, is triangular. This generally correspondsto the sequence shown diagrammatically in FIG. 56D. The triangularprofile of the broached bore 48C is also shown in FIG. 59 .

FIGS. 56E and 56F illustrate an embodiment of the assembly of a softtissue protector or dilator or delivery sleeve 200C with a drill sleeve202C, a guide pin sleeve 204C and a handle 206C. In some embodiments,the drill sleeve 202C and guide pin sleeve 204C can be inserted withinthe soft tissue protector 200C to form a soft tissue protector assembly210C that can slide over the guide pin 208C until bony contact isachieved. The soft tissue protector 200C can be any one of the softtissue protectors or dilators or delivery sleeves disclosed herein. Insome embodiments, an expandable dilator or delivery sleeve 200C asdisclosed herein can be used in place of a conventional soft tissuedilator. In the case of the expandable dilator, in some embodiments, theexpandable dilator can be slid over the guide pin and then expandedbefore the drill sleeve 202C and/or guide pin sleeve 204C are insertedwithin the expandable dilator. In other embodiments, insertion of thedrill sleeve 202C and/or guide pin sleeve 204C within the expandabledilator can be used to expand the expandable dilator.

In some embodiments, a dilator can be used to open a channel though thetissue prior to sliding the soft tissue protector assembly 210C over theguide pin. The dilator(s) can be placed over the guide pin, using forexample a plurality of sequentially larger dilators or using anexpandable dilator. After the channel has been formed through thetissue, the dilator(s) can be removed and the soft tissue protectorassembly can be slid over the guide pin. In some embodiments, theexpandable dilator can serve as a soft tissue protector after beingexpanded. For example, after expansion the drill sleeve and guide pinsleeve can be inserted into the expandable dilator.

As shown in FIGS. 59 and 60 , a triangular implant structure 20C can benow tapped through the soft tissue protector over the guide pin 38Cthrough the ilium, across the SI-Joint, and into the sacrum, until theproximal end of the implant structure 20C is flush against the lateralwall of the ilium (see also FIGS. 61A and 61B). The guide pin 38C andsoft tissue protector are withdrawn, leaving the implant structure 20Cresiding in the broached passageway, flush with the lateral wall of theilium (see FIGS. 61A and 61B). In the illustrated embodiment, twoadditional implant structures 20C are implanted in this manner, as FIG.60 best shows. In other embodiments, the proximal ends of the implantstructures 20C are left proud of the lateral wall of the ilium, suchthat they extend 1, 2, 3 or 4 mm outside of the ilium. This ensures thatthe implants 20C engage the hard cortical portion of the ilium ratherthan just the softer cancellous portion, through which they mightmigrate if there was no structural support from hard cortical bone. Thehard cortical bone can also bear the loads or forces typically exertedon the bone by the implant 20C.

The implant structures 20C are sized according to the local anatomy. Forthe SI-Joint, representative implant structures 20C can range in size,depending upon the local anatomy, from about 35 mm to about 60 mm inlength, and about a 7 mm inscribed diameter (i.e. a triangle having aheight of about 10.5 mm and a base of about 12 mm). The morphology ofthe local structures can be generally understood by medicalprofessionals using textbooks of human skeletal anatomy along with theirknowledge of the site and its disease or injury. The physician is alsoable to ascertain the dimensions of the implant structure 20C based uponprior analysis of the morphology of the targeted bone using, forexample, plain film x-ray, fluoroscopic x-ray, or MRI or CT scanning.

Using a lateral approach, one or more implant structures 20C can beindividually inserted in a minimally invasive fashion across theSI-Joint, as has been described. Conventional tissue access tools,obturators, cannulas, and/or drills can be used for this purpose.Alternatively, the novel tissue access tools described above and in U.S.Provisional Patent Application No. 61/609,043, titled “TISSUE DILATORAND PROTECTER” and filed Mar. 9, 2012, which is hereby incorporated byreference in its entirety, can also be used. No joint preparation,removal of cartilage, or scraping are required before formation of theinsertion path or insertion of the implant structures 20C, so aminimally invasive insertion path sized approximately at or about themaximum outer diameter of the implant structures 20C can be formed.

The implant structures 20C can obviate the need for autologous bonegraft material, additional pedicle screws and/or rods, hollow modularanchorage screws, cannulated compression screws, threaded cages withinthe joint, or fracture fixation screws. Still, in the physician'sdiscretion, bone graft material and other fixation instrumentation canbe used in combination with the implant structures 20C.

In a representative procedure, one to six, or perhaps up to eight,implant structures 20C can be used, depending on the size of the patientand the size of the implant structures 20C. After installation, thepatient would be advised to prevent or reduce loading of the SI-Jointwhile fusion occurs. This could be about a six to twelve week period ormore, depending on the health of the patient and his or her adherence topost-op protocol.

The implant structures 20C make possible surgical techniques that areless invasive than traditional open surgery with no extensive softtissue stripping. The lateral approach to the SI-Joint provides astraightforward surgical approach that complements the minimallyinvasive surgical techniques. The profile and design of the implantstructures 20C minimize or reduce rotation and micromotion. Rigidimplant structures 20C made from titanium provide immediate post-op SIJoint stability. A bony in-growth region 24C comprising a porous plasmaspray coating with irregular surface supports stable bonefixation/fusion. The implant structures 20C and surgical approaches makepossible the placement of larger fusion surface areas designed tomaximize post-surgical weight bearing capacity and provide abiomechanically rigorous implant designed specifically to stabilize theheavily loaded SI-Joint.

To improve the stability and weight bearing capacity of the implant, theimplant can be inserted across three or more cortical walls. Forexample, after insertion the implant can traverse two cortical walls ofthe ilium and at least one cortical wall of the sacrum. The corticalbone is much denser and stronger than cancellous bone and can betterwithstand the large stresses found in the SI-Joint. By crossing three ormore cortical walls, the implant can spread the load across more loadbearing structures, thereby reducing the amount of load borne by eachstructure. In addition, movement of the implant within the bone afterimplantation is reduced by providing structural support in threelocations around the implant versus two locations.

Use of the Implant

The spine (see FIGS. 62A-62C) is a complex interconnecting network ofnerves, joints, muscles, tendons and ligaments, and all are capable ofproducing pain.

The spine is made up of small bones, called vertebrae. The vertebraeprotect and support the spinal cord. They also bear the majority of theweight put upon the spine.

Between each vertebra is a soft, gel-like “cushion,” called anintervertebral disc. These flat, round cushions act like shock absorbersby helping absorb pressure and keep the bones from rubbing against eachother. The intervertebral disc also binds adjacent vertebrae together.The intervertebral discs are a type of joint in the spine.Intervertebral disc joints can bend and rotate a bit but do not slide asdo most body joints.

Each vertebra has two other sets of joints, called facet joints (seeFIG. 62B). The facet joints are located at the back of the spine(posterior). There is one facet joint on each lateral side (right andleft). One pair of facet joints faces upward (called the superiorarticular facet) and the other pair of facet joints faces downward(called the inferior articular facet). The inferior and superior facetjoints mate, allowing motion (articulation), and link vertebraetogether. Facet joints are positioned at each level to provide theneeded limits to motion, especially to rotation and to prevent forwardslipping (spondylolisthesis) of that vertebra over the one below.

In this way, the spine accommodates the rhythmic motions required byhumans to walk, run, swim, and perform other regular movements. Theintervertebral discs and facet joints stabilize the segments of thespine while preserving the flexibility needed to turn, look around, andget around.

Degenerative changes in the spine can adversely affect the ability ofeach spinal segment to bear weight, accommodate movement, and providesupport. When one segment deteriorates to the point of instability, itcan lead to localized pain and difficulties. Segmental instabilityallows too much movement between two vertebrae. The excess movement ofthe vertebrae can cause pinching or irritation of nerve roots. It canalso cause too much pressure on the facet joints, leading toinflammation. It can cause muscle spasms as the paraspinal muscles tryto stop the spinal segment from moving too much. The instabilityeventually results in faster degeneration in this area of the spine.Degenerative changes in the spine can also lead to spondylolysis andspondylolisthesis. Spondylolisthesis is the term used to describe whenone vertebra slips forward on the one below it. This usually occursbecause there is a spondylolysis (defect) in the vertebra on top. Forexample, a fracture or a degenerative defect in the interarticular partsof lumbar vertebra L1 may cause a forward displacement of the lumbarvertebra L5 relative to the sacral vertebra S1 (called L5-S1spondylolisthesis). When a spondylolisthesis occurs, the facet joint canno longer hold the vertebra back. The intervertebral disc may slowlystretch under the increased stress and allow other upper vertebra toslide forward.

An untreated persistent, episodic, severely disabling back pain problemcan easily ruin the active life of a patient. In many instances, painmedication, splints, or other normally-indicated treatments can be usedto relieve intractable pain in a joint. However, in for severe andpersistent problems that cannot be managed by these treatment options,degenerative changes in the spine may require a bone fusion surgery tostop both the associated disc and facet joint problems.

A fusion is an operation where two bones, usually separated by a joint,are allowed to grow together into one bone. The medical term for thistype of fusion procedure is arthrodesis.

Lumbar fusion procedures have been used in the treatment of pain and theeffects of degenerative changes in the lower back. A lumbar fusion is afusion in the S1-L5-L4 region in the spine.

One conventional way of achieving a lumbar fusion is a procedure calledanterior lumbar interbody fusion (ALIF). In this procedure, the surgeonworks on the spine from the front (anterior) and removes a spinal discin the lower (lumbar) spine. The surgeon inserts a bone graft into thespace between the two vertebrae where the disc was removed (theinterbody space). The goal of the procedure is to stimulate thevertebrae to grow together into one solid bone (known as fusion). Fusioncreates a rigid and immovable column of bone in the problem section ofthe spine. This type of procedure is used to try and reduce back painand other symptoms.

Facet joint fixation procedures have also been used for the treatment ofpain and the effects of degenerative changes in the lower back. Theseprocedures take into account that the facet joint is the only truearticulation in the lumbosacral spine. In one conventional procedure forachieving facet joint fixation, the surgeon works on the spine from theback (posterior). The surgeon passes screws from the spinous processthrough the lamina and across the mid-point of one or more facet joints.

Conventional treatment of spondylolisthesis may include a laminectomy toprovide decompression and create more room for the exiting nerve roots.This can be combined with fusion using, e.g., an autologous fibulargraft, which may be performed either with or without fixation screws tohold the bone together. In some cases the vertebrae are moved back tothe normal position prior to performing the fusion, and in others thevertebrae are fused where they are after the slip, due to the increasedrisk of injury to the nerve with moving the vertebra back to the normalposition.

Currently, these procedures entail invasive open surgical techniques(anterior and/or posterior). Further, ALIF entails the surgical removalof the disc. Like all invasive open surgical procedures, such operationson the spine risk infections and require hospitalization. Invasive opensurgical techniques involving the spine continue to be a challenging anddifficult area.

A. Use of the Implant Structures to Achieve Anterior Lumbar InterbodyFusion

FIG. 63 shows, in an exploded view prior to implantation, arepresentative configuration of an assembly of one or more implantstructures 20C sized and configured to achieve anterior lumbar interbodyfusion, in a non-invasive manner and without removal of theintervertebral disc. FIGS. 64 to 66 show the assembly afterimplantation, respectively, in an anterior view, a right lateral view,and a superior left lateral perspective view.

In the representative embodiment illustrated in FIGS. 64 to 66 , theassembly comprises three implant structures 20C. It should beappreciated, however, that a given assembly can include a greater orlesser number of implant structures 20C.

In the representative embodiment shown in FIGS. 64 to 66 , the threeimplant structures 20C are spaced in an adjacent lateral array. Theimplant structures 20C extend from an anterolateral region of a selectedvertebral body (i.e., a lateral region anterior to a transverseprocess), across the intervertebral disc into an opposite anterolateralregion of an adjacent caudal (inferior) vertebra. As shown in FIGS. 64to 66 , the array of implant structures 20C extends in an angled path(e.g., about 20° to about 40° off horizontal) through the cranial(superior) lumbar vertebral body (shown as L4) in an inferior direction,through the adjoining intervertebral disc, and terminates in the nextadjacent caudal (inferior) lumbar vertebral body (shown as L5).

More particularly, in the representative embodiment shown in FIGS. 63 to66 , the implant structures 20C enter the right anterolateral region ofvertebra L4 and terminate within the left anterolateral interior ofvertebra L5, spanning the intervertebral disc between L4 and L5.

Alternatively, or in combination, an array of implant structures 20C canlikewise extend between L5 and S1 in the same trans-disc formation.

The implant structures 20C are sized according to the local anatomy. Theimplant structures 20C can be sized differently, e.g., 3 mm, 4 mm, 6 mm,etc.), to accommodate anterolateral variations in the anatomy. Theimplant structures 20C can be sized for implantation in adults orchildren.

The intimate contact created between the bony in-growth orthrough-growth region 24C along the surface of the implant structure 20Caccelerates bony in-growth or through-growth onto, into, or through theimplant structure 20C, to accelerate trans-disc fusion between theselumbar vertebrae.

FIGS. 67A to 67G diagrammatically show, for purposes of illustration, arepresentative lateral (or posterolateral) procedure for implanting theassembly of implant structures 20C shown in FIGS. 64 to 66 .

The physician identifies the vertebrae of the lumbar spine region thatare to be fused using, e.g., the Faber Test, or CT-guided injection, orX-ray/MRI of the lumbar spine. Aided by lateral and anterior-posterior(A-P) c-arms, and with the patient lying in a prone position (on theirstomach), the physician makes a 3 mm incision laterally orposterolaterally from the side (see FIG. 67A). Aided by conventionalvisualization techniques, e.g., using X-ray image intensifiers such as aC-arms or fluoroscopes to produce a live image feed which is displayedon a TV screen, a guide pin 38C is introduced by conventional means intoL4 (see FIG. 67B) for the first, most anterolateral implant structure(closest to the right transverse process of L4), in the desired angledinferiorly-directed path through the intervertebral disc and into theinterior left anterolateral region of vertebra L5.

When the guide pin 38C is placed in the desired orientation, thephysician desirable slides a soft tissue protector over the guide pin38C before proceeding further. To simplify the illustration, the softtissue protector is not shown in the drawings.

Through the soft tissue protector, a cannulated drill bit 40C is nextpassed over the guide pin 38C (see FIG. 67C). The cannulated drill bit40C forms a pilot insertion path or bore 42C along the first angled pathdefined by the guide pin 38C. A single drill bit or multiple drill bits40C can be employed to drill through bone fragments or bone surfaces tocreate a pilot bore 42C of the desired size and configuration.

When the pilot bore 42C is completed, the cannulated drill bit 40C iswithdrawn over the guide pin 38C.

Through the soft tissue protector, a broach 44C having the externalgeometry and dimensions matching the external geometry and dimensions ofthe implant structure 20C (which, in the illustrated embodiment, istriangular) (see FIG. 67D) is tapped through the soft tissue protectorover the guide pin 38C and into the pilot bore 42C. The shaped broach44C cuts along the edges of the pilot bore 42C to form the desiredprofile (which, in the illustrated embodiment, is triangular) toaccommodate the implant structure 20C.

The broach 44C is withdrawn (see FIG. 67E), and the first, mostanterolateral implant structure 20C is passed over the guide pin 38Cthrough the soft tissue protector into the broached bore 48C. The guidepin 38C and soft tissue protector are withdrawn from the first implantstructure 20C.

The physician repeats the above-described procedure sequentially for thenext anterolateral implant structures 20C: for each implant structure,inserting the guide pin 38C, forming the pilot bore, forming thebroached bore, inserting the respective implant structure, withdrawingthe guide pin, and then repeating the procedure for the next implantstructure, and so on until all implant structures 20C are placed (asFIGS. 67F and 67G indicate). The incision site(s) are closed.

In summary, the method for implanting the assembly of the implantstructures 20C comprises (i) identifying the bone structures to be fusedand/or stabilized; (ii) opening an incision; (iii) using a guide pin toestablished a desired implantation path through bone for the implantstructure 20C; (iv) guided by the guide pin, increasing the crosssection of the path; (v) guided by the guide pin, shaping the crosssection of the path to correspond with the cross section of the implantstructure 20C; (vi) inserting the implant structure 20C through the pathover the guide pin; (vii) withdrawing the guide pin; (viii) repeating,as necessary, the procedure sequentially for the next implantstructure(s) until all implant structures 20C contemplated areimplanted; and (ix) closing the incision.

As FIGS. 68 and 69 show, assemblies comprising one or more implantstructures 20C can be inserted from left and/or right anterolateralregions of a given lumbar vertebra, in an angled path through theintervertebral disc and into an opposite anterolateral interior regionof the next inferior lumbar vertebra.

For purposes of illustration, FIG. 68 shows two implant structures 20Centering on the right anterolateral side of L4, through theintervertebral disc and into the left anterolateral region of L5, andone implant structure 20C entering on the left anterolateral side of L4,through the intervertebral disc and into the right anterolateral regionof L5. In this arrangement, the left and right implant structures 20Ccross each other in transit through the intervertebral disc.

As another illustration of a representative embodiment, FIG. 69 showsone implant structure 20C entering on the right anterolateral side ofL4, through the intervertebral disc and into the left anterolateralregion of L5, and one implant structure 20C entering on the leftanterolateral side of L4, through the intervertebral disc and into theright anterolateral region of L5. In this arrangement as well, the leftand right implant structures 20C cross each other in transit through theintervertebral disc.

B. Use of Implant Structures to Achieve Translaminal Lumbar Fusion(Posterior Approach)

FIG. 70 shows, in an exploded view prior to implantation, arepresentative configuration of an assembly of one or more implantstructures 20C sized and configured to achieve translaminar lumbarfusion in a non-invasive manner and without removal of theintervertebral disc. FIG. 71 shows the assembly after implantation,respectively, in an inferior transverse plane view.

As can be seen in the representative embodiment illustrated in FIGS. 70and 71 , the assembly comprises two implant structures 20C. The firstimplant structure 20C extends from the left superior articular processof vertebra L5, through the adjoining facet capsule into the leftinferior articular process of vertebra L4, and, from there, furtherthrough the lamina of vertebra L4 into an interior right posterolateralregion of vertebra L4 adjacent the spinous process. The second implantstructure 20C extends from the right superior articular process ofvertebra L5, through the adjoining facet capsule into the right inferiorarticular process of vertebra L4, and, from there, further through thelamina of vertebra L4 into an interior left posterolateral region ofvertebra L4 adjacent the spinous process. The first and second implantstructures 20C cross each other within the medial lamina of vertebra L4.

The first and second implant structures 20C are sized and configuredaccording to the local anatomy. The selection of a translaminar lumbarfusion (posterior approach) is indicated when the facet joints arealigned with the sagittal plane. Removal of the intervertebral disc isnot required, unless the condition of the disc warrants its removal.

A procedure incorporating the technical features of the procedure shownin FIGS. 67A to 67G can be tailored to a posterior procedure forimplanting the assembly of implant structures 20C shown in FIGS. 70 and71 . The method comprises (i) identifying the vertebrae of the lumbarspine region that are to be fused; (ii) opening an incision, whichcomprises, e.g., with the patient lying in a prone position (on theirstomach), making a 3 mm posterior incision; and (iii) using a guide pinto established a desired implantation path through bone for the first(e.g., left side) implant structure 20C, which, in FIGS. 70 and 71 ,traverses through the left superior articular process of vertebra L5,through the adjoining facet capsule into the left inferior articularprocess of vertebra L4, and then through the lamina of vertebra L4 intoan interior right posterolateral region of vertebra L4 adjacent thespinous process. The method further includes (iv) guided by the guidepin, increasing the cross section of the path; (v) guided by the guidepin, shaping the cross section of the path to correspond with the crosssection of the implant structure; (vi) inserting the implant structure20C through the path over the guide pin; (vii) withdrawing the guidepin; and (viii) using a guide pin to established a desired implantationpath through bone for the second (e.g., right side) implant structure20C, which, in FIGS. 70 and 71 , traverses through the right superiorarticular process of vertebra L5, through the adjoining facet capsuleinto the right inferior articular process of vertebra L4, and throughthe lamina of vertebra L4 into an interior left posterolateral region ofvertebra L4 adjacent the spinous process. The physician repeats theremainder of the above-described procedure sequentially for the rightimplant structure 20C as for the left, and, after withdrawing the guidepin, closes the incision.

The intimate contact created between the bony in-growth orthrough-growth region 24C along the surface of the implant structure 20Cacross the facet joint accelerates bony in-growth or through-growthonto, into, or through the implant structure 20C, to accelerate fusionof the facets joints between L4 and L5. Of course, translaminar lumbarfusion between L5 and S1 can be achieved using first and second implantstructures in the same manner.

C. Use of Implant Structures to Achieve Lumbar Facet Fusion (PosteriorApproach)

FIG. 72 shows, in an exploded view prior to implantation, arepresentative configuration of an assembly of one or more implantstructures 20C sized and configured to lumbar facet fusion, in anon-invasive manner and without removal of the intervertebral disc.FIGS. 73 and 74 show the assembly after implantation, respectively, inan inferior transverse plane view and a lateral view.

As can be seen in the representative embodiment illustrated in FIGS. 72and 74 , the assembly comprises two implant structures 20C. The firstimplant structure 20C extends from the left inferior articular processof vertebra L4, through the adjoining facet capsule into the leftsuperior articular process of vertebra L5 and into the pedicle ofvertebra L5. The second implant structure 20C extends from the rightinferior articular process of vertebra L5, through the adjoining facetcapsule into the right superior articular process of vertebra L5 andinto the pedicle of vertebra L5. In this arrangement, the first andsecond implant structures 20C extend in parallel directions on the leftand right pedicles of vertebra L5. The first and second implantstructures 20C are sized and configured according to the local anatomy.The selection of lumbar facet fusion (posterior approach) is indicatedwhen the facet joints are coronally angled. Removal of theintervertebral disc is not necessary, unless the condition of the discwarrants its removal.

A procedure incorporating the technical features of the procedure shownin FIGS. 67A to 67G can be tailored to a posterior procedure forimplanting the assembly of implant structures 20C shown in FIGS. 72 to74 . The method comprises (i) identifying the vertebrae of the lumbarspine region that are to be fused; (ii) opening an incision, whichcomprises, e.g., with the patient lying in a prone position (on theirstomach), making a 3 mm posterior incision; and (iii) using a guide pinto established a desired implantation path through bone for the first(e.g., left side) implant structure 20C, which, in FIGS. 72 to 74 ,traverses through the left inferior articular process of vertebra L4,through the adjoining facet capsule into the left superior articularprocess of vertebra L5 and into the pedicle of vertebra L5. The methodfurther includes (iv) guided by the guide pin, increasing the crosssection of the path; (v) guided by the guide pin, shaping the crosssection of the path to correspond with the cross section of the implantstructure 20; (vi) inserting the implant structure 20C through the pathover the guide pin; (vii) withdrawing the guide pin; and (viii) using aguide pin to established a desired implantation path through bone forthe second (e.g., right side) implant structure 20C, which, in FIGS. 72to 74 , traverses through the right inferior articular process ofvertebra L5, through the adjoining facet capsule into the right superiorarticular process of vertebra L5 and into the pedicle of vertebra L5.The physician repeats the remainder of the above-described proceduresequentially for the right implant structure 20C as for the left and,withdrawing the guide pin, closes the incision.

The intimate contact created between the bony in-growth orthrough-growth region 24C along the surface of the implant structure 20Cacross the facet joint accelerates bony in-growth or through-growthonto, into, or through the implant structure 20C, to accelerate fusionof the facets joints between L4 and L5.

Of course, translaminar lumbar fusion between L5 and S1 can be achievedusing first and second implant structures in the same manner.

D. Use of Implant Structures to Achieve Trans-Iliac Lumbar Fusion(Anterior Approach)

FIG. 75A shows, in an exploded view prior to implantation, arepresentative configuration of an assembly of one or more implantstructures 20C sized and configured to achieve fusion between lumbarvertebra L5 and sacral vertebra S1, in a non-invasive manner and withoutremoval of the intervertebral disc. FIG. 75B shows the assembly afterimplantation.

In the representative embodiment illustrated in FIGS. 75A and 75B, theassembly comprises two implant structures 20C. It should be appreciated,however, that a given assembly can include a greater or lesser number ofimplant structures 20C.

As FIGS. 75A and 75B show, the assembly comprises two implant structures20C inserted from left and right anterolateral regions of lumbarvertebra L5, in an angled path (e.g., about 20.degree. to about40.degree. off horizontal) through the intervertebral disc in aninferior direction, into and through opposite anterolateral interiorregions of sacral vertebra 51, through the sacro-iliac joint, andterminating in the ilium. In this arrangement, the left and rightimplant structures 20C cross each other in transit through theintervertebral disc. As before described, the implant structures 20C aresized according to the local anatomy.

The intimate contact created between the bony in-growth orthrough-growth region 24C along the surface of the implant structure 20Caccelerates bony in-growth or through-growth onto, into, or through theimplant structure 20C, to accelerate lumbar trans-iliac fusion betweenvertebra L5 and S1.

A physician can employ the lateral (or posterolateral) procedure asgenerally shown in FIGS. 67A to 67G for implanting the assembly ofimplant structures 20C shown in FIGS. 75A and 75B, including forming apilot bore over a guide pin inserted in the angled path, forming abroached bore, inserting the right implant 20C structure, withdrawingthe guide pin, and repeating for the left implant structure 20C, or viceversa. The incision site(s) are closed.

The assembly as described makes possible the achievement of trans-iliaclumbar fusion using an anterior in a non-invasive manner, with minimalincision, and without necessarily removing the intervertebral discbetween L5 and S1.

E. Use of Implant Structures to Achieve Trans-Iliac Lumbar Fusion(Postero-Lateral Approach from Posterior Iliac Spine)

FIG. 76A shows, in an exploded view prior to implantation, anotherrepresentative configuration of an assembly of one or more implantstructures 20C sized and configured to achieve fusion between lumbarvertebra L5 and sacral vertebra 51, in a non-invasive manner and withoutremoval of the intervertebral disc. FIGS. 76B and 76C show the assemblyafter implantation.

As FIGS. 76A and 76B show, the one or more implant structures areintroduced in a postero-lateral approach entering from the posterioriliac spine of the ilium, angling through the SI-Joint into and throughthe sacral vertebra 51, and terminating in the lumbar vertebra L5. Thispath and resulting placement of the implant structures 20C are alsoshown in FIG. 76C. In the illustrated embodiment, two implant structures20C are placed in this manner, but there can be more or fewer implantstructures 20C. Also in the illustrated embodiment, the implantstructures 20C are triangular in cross section, but it should beappreciated that implant structures 20C of other cross sections aspreviously described can be used.

The postero-lateral approach involves less soft tissue disruption thatthe lateral approach, because there is less soft tissue overlying theentry point of the posterior iliac spine of the ilium. Introduction ofthe implant structure 20C from this region therefore makes possible asmaller, more mobile incision.

The set-up for a postero-lateral approach is generally the same as for alateral approach. It desirably involves the identification of the lumbarregion that is to be fixated or fused (arthrodesed) using, e.g., theFaber Test, or CT-guided injection, or X-ray/MRI of SI Joint. It isdesirable performed with the patient lying in a prone position (on theirstomach) and is aided by lateral and anterior-posterior (A-P) c-arms.The same surgical tools are used to form the pilot bore over a guide pin(e.g., on the right side), except the path of the pilot bore now startsfrom the posterior iliac spine of the ilium, angles through theSI-Joint, and terminates in the lumbar vertebra L5. The broached bore isformed, and the right implant 20C structure is inserted. The guide pinis withdrawn, and the procedure is repeated for the left implantstructure 20C, or vice versa. The incision site(s) are closed.

The assembly as described makes possible the achievement of trans-iliaclumbar fusion using a postero-lateral approach in a non-invasive manner,with minimal incision, and without necessarily removing theintervertebral disc between L5 and S1.

F. Use of Implant Structures to Stabilize a Spondylolisthesis

FIG. 77 shows a spondylolisthesis at the L5/S1 articulation, in whichthe lumbar vertebra L5 is displaced forward (anterior) of the sacralvertebra S1. As FIG. 77 shows, the posterior fragment of L5 remains innormal relation to the sacrum, but the anterior fragment and the L5vertebral body has moved anteriorly. Spondylolisthesis at the L5/S1articulation can result in pressure in the spinal nerves of the caudaequine as they pass into the superior part of the sacrum, causing backand lower limb pain.

FIG. 78A shows, in an exploded view prior to implantation, arepresentative configuration of an assembly of one or more implantstructures 20C sized and configured to stabilize the spondylolisthesisat the L5/S1 articulation. FIGS. 78B and 78C show the assembly afterimplantation.

As shown, the implant structure 20C extends from a posterolateral regionof the sacral vertebra 51, across the intervertebral disc into anopposite anterolateral region of the lumbar vertebra L5. The implantstructure 20C extends in an angled path (e.g., about 20.degree. to about40.degree. off horizontal) through the sacral vertebra 51 in a superiordirection, through the adjoining intervertebral disc, and terminates inthe lumbar vertebra L5.

A physician can employ a posterior approach for implanting the implantstructure 20C shown in FIGS. 78A, 78B, and 78C, which includes forming apilot bore over a guide pin inserted in the angled path from theposterior of the sacral vertebra 51 through the intervertebral disc andinto an opposite anterolateral region of the lumbar vertebra L5, forminga broached bore, inserting the implant structure 20C, and withdrawingthe guide pin. The incision site is then closed. As previouslydescribed, more than one implant structure 20C can be placed in the samemanner to stabilize a spondylolisthesis. Furthermore, a physician canfixate the implant structure(s) 20C using the anterior trans-iliaclumbar path, as shown in FIG. 75A/B or 76A/B/C.

The physician can, if desired, combine stabilization of thespondylolisthesis, as shown in FIG. 78A/B/C, with a reduction,realigning L5 and S-1. The physician can also, if desired, combinestabilization of the spondylolisthesis, as shown in FIG. 78A/B/C (withor without reduction of the spondylolisthesis), with a lumbar facetfusion, as shown in FIGS. 72 to 74 . The physician can also, if desired,combine stabilization of the spondylolisthesis, as shown in FIG.78A/B/C, with a decompression, e.g., by the posterior removal of thespinous process and laminae bilaterally.

Removal of Implant

In some situations, it may be desirable to remove the implant structure20C from the patient after implantation. However, bone ingrowth overtime into the bony in-growth region 24C of the implant 20C can makeremoval difficult and require the separation of the implant structure20C from the bone. In some embodiments, osteotomes can be used to chiseland cut out the implant structure 20C from the bone.

FIGS. 79A-79C illustrate an embodiment of an implant removal system thatis based on a single bladed osteotome 2500C for removing an implantstructure 20C from bone. As illustrated in FIG. 79A, the single bladedosteotome 2500C can have a flat, elongate body 2502C with a proximal end2504C and a distal end 2506C. The distal end 2506C can terminate in ablade portion 2508C having a sharp edge, like a chisel, for cuttingbone. In some embodiments, the blade portion 2508C can be oriented at anangle that is substantially perpendicular to the longitudinal axis ofthe elongate body 2502C. In other embodiments, the blade portion 2508Ccan be oriented at an oblique angle with respect to the longitudinalaxis of the elongate body 2502C. In some embodiments, the blade portion2508C has a straight edge or a curved edge. In some embodiments, theblade portion 2508C U-shaped. In some embodiments, the blade portion2508C has a width equal to that of one of the faces or sides of therectilinear implant structure 20C. In other embodiments, the width ofthe blade portion 2508C can be slightly less than or slightly greaterthan the width of one of the faces or sides of the implant structure20C. Slightly less can mean up to 5, 10, 15, or 20% less, and slightlymore can mean up to 5, 10, 15 or 20% more. The proximal end 2504C canterminate in a head 2510C with a flat surface 2512C for striking.

As shown in FIGS. 79B-79D, the single bladed osteotome 2500C can be usedwith an osteotome guide 2520C having a plurality of channels 2522C forreceiving the single bladed osteotome 2500C. In some embodiments, thenumber of channels 2522C matches the number of sides of the rectilinearimplant structure 20C. The osteotome guide 252C0 can have across-sectional shape and size that generally matches thecross-sectional shape and size of the implant structure 20C, with thechannels 2522C located along each face of the osteotome guide 2520C suchthat the single bladed osteotome 2500C can be aligned with the faces orsides of the implant structure 20C. In some embodiments, the corners ofthe osteotome guide 2520C between adjacent faces can be hollowed orscooped out to reduce the amount of materials used to fabricate theosteotome guide, thereby reducing the costs and weight of the device.The osteotome guide 2520C can be cannulated and have a lumen 2524C forreceiving a guide pin 2540C that can be inserted into the lumen of theimplant structure 20C. In some embodiments, one or more faces of theosteotome guide 2520C can have a receptacle 2526C for receiving a stop2509C that can be used to fix in place a blade 2501C disposed within thechannel 2522C.

As illustrated in FIGS. 79E-79G, the blade 2501C can be a blank thatfits within the channel 2522C with a length that is slightly longer thanthe length of the osteotome guide 2520C, allowing the blade 2501C to beinserted into the channel and tapped into the bone to secure thealignment of the osteotome guide 2520C over the implant to be removed.The blade 2501C can have a chiseled end 2503C for biting into the boneand a proximal end 2505C that is wider than the channel 2522C to limitthe penetration of the blade 2501C into the bone to a predetermineddepth. The blade 2501C can also have a receptacle 2507C for receivingthe stop 2509C. The stop 2509C can be a nut with a knurled or texturedgripping portion 2511C and can be attached to the receptacle of theblade 2501C or the osteotome guide by any means, such as complementarythreads and grooves, for example.

In some embodiments as illustrated in FIG. 79H, the guide pin 2540C canhave a distal portion 2542C that can be inserted into the lumen of theimplant 20C. In some embodiments, the distal portion 2542C can bethreaded and can be fastened and secured to the implant structure 20C byscrewing the threaded end into complementary threads in the lumen of theimplant structure 20C. In some embodiments, the proximal portion 2544Cof the guide pin 2540C can be threaded so that a pull shaft 2546C forpulling out the implant 20C, illustrated in FIG. 79I, can be attached tothe proximal portion 2544C of the guide pin 2540C. The pull shaft 2546Ccan have a knurled or textured handle portion 2547C for gripping. Afterthe guide pin 2540C is inserted into the implant structure 20C, theosteotome guide 2520C can be disposed over the guide pin 2540C until theosteotome guide 2520C abuts against the bone. Alternatively, in someembodiments, the osteotome guide 2520C can be held about 3 to 5 mm, or 1to 10 mm proud of the bone surface, such as the ileum or vertebra, byusing a stop and/or collar, described below.

In some embodiments as illustrated in FIGS. 79J and 79K, the osteotomeguide 2520C can be used in conjunction with a dilator 2530C having alumen sized to receive the osteotome guide 2520C. In some embodiments,the distal end of the dilator 2530C can have one or more cutouts 2532Cthat allow the dilator 2530C to be centered over one implant structurewhile allowing the distal rim of the dilator 2530C to be placed overother implant structures 20 or other structures that extend out of thebone surface. The cutouts 2532C are particularly useful when there is acluster of implant structures 20C embedded in the bone in one area andin relatively close proximity. The dilator 2530C can be rotated to lineup the cutouts 2532C with any implant structures 20C surrounding thecentered implant structure 20C. In some embodiments, the cutouts 2532Ccan be curved or arched such as semicircular, while in otherembodiments, the cutouts can be rectilinear, such as rectangular orsquare.

In some embodiments as illustrated in FIG. 79L, the osteotome guide2520C can have an adjustable collar 2521C that can be fastened along aplurality of positions along the osteotome guide 2520C. In someembodiments, the collar 2521C can be fastened and secured to theosteotome guide 2520C using the stop 2509C and receptacle 2526C. Thedilator 2530C can be disposed over the guide pin 2540C until it abutsagainst the bone. Then the osteotome guide 2520C can be disposed overthe guide pin 2540C and into the lumen of the dilator 2530C until thecollar 2521C on the osteotome guide 2520C abuts against the proximal endof the dilator 2530C. The collar 2521C can be adjusted and positionedsuch that the distal end of the osteotome guide 2520C is left proud,i.e. above, the surface of the bone as set forth above. In someembodiments, the osteotome guide 2520C is left proud of the bone surfacebecause the proximal end of the implant structure 20C itself is proud ofthe bone surface, and therefore, the collar 2521C prevents the distalend of the osteotome guide 2520C from striking or pushing into theproximal end of the implant structure 20C.

FIGS. 79M and 79N illustrate the removal system as assembled. Once theguide pin 2540C, dilator 2530C, and osteotome guide 2520C are in placeand aligned over the implant structure 20C to be removed, the singlebladed osteotome 2500C can be inserted into the channel 2522C in theosteotome guide 2520C and pushed into contact with the bone surroundingthe implant structure 20C. When the osteotome guide 2520C is properlyaligned, the blade portion 2508C of the single bladed osteotome 2500Cwill be aligned with one face or side of the implant structure 20C. Insome embodiments, a blade 2501C that can be inserted into the channels2522C can be used to help align the osteotome guide 2520C with theimplant structure 20C. In some embodiments, the channels 2522C arepositioned such that the spacing between the blade portion 2510C of theosteotome and face of the implant is about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6,0.7, 0.8, 0.9 or 1.0 mm or less. After the osteotome guide 2520C hasbeen aligned and the one or more faces of the implant have been cutfree, the blade 2501C can be removed and the single bladed osteotome2500C can be inserted into the channel 2522C to cut the remaining face.The single bladed osteotome 2500C can be advanced into the bone bystriking the head 2510C of the osteotome 2500C with a hammer or someother striking device. The osteotome 2500C can include markings toindicate the depth of penetration of the osteotome 2500C into the bone.In addition, the osteotome 2500C can include an adjustable stop to limitthe depth of penetration of the osteotome 2500C to a predetermineddepth. For example, the stop on the osteotome 2500C can be set to limitthe depth of penetration to the depth of the implant structure 20C inthe bone, thereby reducing or eliminating the chance of excesspenetration which can lead to damage of nerve tissue and other sensitivetissues. Once the proper depth has been reached, the osteotome 2500C canbe removed from the first channel 2522C and inserted into the secondchannel 2522C to cut the bone along the second face or side of theimplant structure 20C. This process can be repeated until all sides ofthe implant structure 20C have been cut away from the bone. For example,for removing an implant structure 20C with a triangular cross-section,the osteotome would be used three times in an osteotome guide 2520C withthree channels to cut the bone away from each face or side of theimplant structure 20C. The guide pin 2540C which can be screwed into andattached to the implant structure 20C can be used to pull the cutoutimplant structure 20C out of the bone. This method of implant structureremoval does not require torque to be applied to the implant structure,in contrast to removal of screw type implants.

FIGS. 80A-80D illustrate an embodiment of double bladed removal systembased on a double bladed osteotome 2600C having elongate body 2602C witha first flat and elongate section 2604C and a second flat and elongatesection 2606C that are joined together at an angle that corresponds tothe angle between two adjacent faces of the rectilinear implantstructure 20C. For example, for an implant structure 20C with atriangular cross-sectional profile, the angle between the faces of theimplant structure 20C can be 60 degrees, and therefore, the anglebetween the first flat and elongate section 2604C and second flat andelongate section 2606C can also be 60 degrees. Triangles havingdifferent angles are also contemplated as well as the angles found inother rectilinear geometries, such as 90 degree angles for rectangularand square cross-sections. In some embodiments, the width of first flatand elongate section 2604C and the second flat and elongate section2606C can be substantially equivalent to the width of two adjacent facesof the implant structure 20C. In some embodiments, the width of firstflat and elongate section 2604C and the second flat and elongate section2606C can be slightly larger than the width of two adjacent faces of theimplant structure 20C in order to accommodate the gap between the doublebladed osteotome 2600C and the implant structure 20C during the cuttingprocess and to ensure that the entire face of each face of the implantis cut away from the ingrown bone. The distal ends of the first flat andelongate section 2604C and the second flat and elongate section 2606Ccan terminate in a first bladed portion 2608C and a second bladedportion 2610C, respectively, that together form a V shaped bladedportion 2609C. The proximal portion of the double bladed osteotome 2600Ccan terminate in a head 2612C with a surface 2614C for striking.

In some embodiments, the double bladed osteotome 2600C can have aproximal portion 2616C that is cannulated with a lumen 2618C forreceiving a guide pin 2540C that can be attached to the implantstructure 20C as described above. The V shaped bladed portion 2609C canbe offset from the axis of the lumen 2618C such that when the doublebladed osteotome 2600C is disposed over the guide pin 38C the V shapedbladed portion 2609C can be rotated until it is aligned with two facesof the implant structure 20C. The V shaped bladed portion 2609C isitself a self-aligning feature that facilitates the alignment of the Vshaped bladed portion 2609C with the faces of the implant structure 20C.For example, the apex of the V shaped bladed portion 2609C can bealigned with a corner of implant structure 20C that joins two faces. Inaddition, the osteotome 2600C can be used with a dilator 2530C asdescribed above. Once the V shaped bladed portion 2609C is aligned withthe implant structure 20C, the double bladed osteotome 2600C can beadvanced to cut the bone through impacts to the head 2612C of theosteotome 2600C. The spacing between the blade portion 2609C and theface of the implant can be the same as described above for the singlebladed osteotome. Stop features to prevent excess advancement into boneand depth indicators can also be included or attached to the guide pin2540C and/or the osteotome 2600C. The osteotome 2600C can be retracted,rotated and aligned to cut the remaining faces of implant structure 20Cfrom the bone. For an implant structure 20C having three or four faces,two cuts are needed to cut every face of the implant structure 20C fromthe bone. As described above, after the faces of the implant structure20C have been cut from the bone, the guide pin 2540C, which can bescrewed into the implant structure 20C, can be pulled in order to removethe implant structure 20C from the bone.

In some embodiments, the width of first flat and elongate section 2604Cand the second flat and elongate section 2606C can each be about halfthe width of the faces of the implant structure 20C, or slightly morethan half the width of the faces of the implant structure 20C. In thisembodiment, the number of cuts needed to cut each face of the implantstructure 20C from the bone is equal to the number of faces of theimplant structure 20C.

In some embodiments as illustrated in FIGS. 80C and 80D, the doublebladed osteotome 2600C can be used with an osteotome guide 2620C havingchannels 2622C for receiving the double bladed osteotome 2600C, similarto the osteotome guide describe above expect that the channels are sizedand shaped to receive the double bladed osteotome 2600C. As describedabove, the osteotome guide 2620C can be used with a dilator 2530C. Insome embodiments, the osteotome guide 2620C can have one channel toreceive a double bladed osteotome and another channel to receive asingle bladed osteotome. The osteotome guide 2620C can have a lumen2624C for receiving the guide pin.

In some embodiments, as the width of the bladed portion of the osteotomeis increased, the greater the friction and/or resistance that occurswhen the osteotome is advanced through the bone. Therefore, if thesurgeon encounters too much resistance when trying to advance the adouble bladed osteotome, the surgeon can switch to a smaller doublebladed osteotome or a single bladed osteotome. In some embodiments, thethickness of the blade portion of the osteotome can be less than about2.5, 2.25, 2.0, 1.75, 1.5, 1.25, or 1.0 mm, or between about 1.0 to 2.5mm or 1.25 to 2.25 mm or 1.5 to 2.0 mm Increasing the thickness of theblade portion increases the durability and the capability of theosteotome to tolerate the high forces generated during impact into thebone, but at the cost of increasing friction and/or resistance.

The implant structure 20C may be removed for a variety of reasons. Insome situations, it can be desirable to replace an old implant with anew implant, for example in an implant rescue procedure. The proceduresdescribed above can be used to remove the old implant structure, leavinga cavity that is slightly larger than the original implant structure. Toprovide a tight fit within the cavity, the new implant structure can belarger than the old implant structure. In some embodiments, the newimplant structure can be between about 0.25 to 2.0 mm, or 0.5 to 1.0 mmlarger for each face of the new implant. This sizing can be particularlyappropriate when replacement of the old implant occurs relatively soonafter the original implantation procedure, such as less than 1, 2, 3, or4 weeks after the original implantation procedure, because the boneingrowth into the old implant structure is less than an implantstructure than has been implanted for a long time, such as over 1, 2, 3,4, 6, or 12 months. Removal of old implants residing in the bone for along time may be more difficult due to increased bone ingrowth, andconsequently, the cavity after removal may be larger. In this situation,a larger new implant can be used, having each face being about 2 mmlarger than the old implant structure. In some embodiments, the surgeoncan measure the size of the cavity and select the appropriately sizednew implant.

II. Conclusion

The various representative embodiments of the assemblies of the implantstructures 20, as described, make possible the achievement of diverseinterventions involving the fusion and/or stabilization of lumbar andsacral vertebra in a non-invasive manner, with minimal incision, andwithout the necessitating the removing the intervertebral disc. Therepresentative lumbar spine interventions described can be performed onadults or children and include, but are not limited to, lumbar interbodyfusion; translaminar lumbar fusion; lumbar facet fusion; trans-iliaclumbar fusion; and the stabilization of a spondylolisthesis. It shouldbe appreciated that such interventions can be used in combination witheach other and in combination with conventional fusion/fixationtechniques to achieve the desired therapeutic objectives.

Significantly, the various assemblies of the implant structures 20C asdescribed make possible lumbar interbody fusion without the necessity ofremoving the intervertebral disc. For example, in conventional anteriorlumbar interbody fusion procedures, the removal of the intervertebraldisc is a prerequisite of the procedure. However, when using theassemblies as described to achieve anterior lumbar interbody fusion,whether or not the intervertebral disc is removed depends upon thecondition of the disc, and is not a prerequisite of the procedureitself. If the disc is healthy and has not appreciably degenerated, oneor more implant structures 20C can be individually inserted in aminimally invasive fashion, across the intervertebral disc in the lumbarspine area, leaving the disc intact.

In all the representative interventions described, the removal of adisc, or the scraping of a disc, is at the physician's discretion, basedupon the condition of the disc itself, and is not dictated by theprocedure. The bony in-growth or through-growth regions 24C of theimplant structures 20C described provide both extra-articular and intraosseous fixation, when bone grows in and around the bony in-growth orthrough-growth regions 24C.

Conventional tissue access tools, obturators, cannulas, and/or drillscan be used during their implantation. No disc preparation, removal ofbone or cartilage, or scraping are required before and during formationof the insertion path or insertion of the implant structures 20C, so aminimally invasive insertion path sized approximately at or about themaximum outer diameter of the implant structures 20C need be formed.Still, the implant structures 20C, which include the elongated bonyin-growth or through-growth regions 24C, significantly increase the sizeof the fusion area, from the relatively small surface area of a givenjoint between adjacent bones, to the surface area provided by anelongated bony in-growth or through-growth regions 24C. The implantstructures 20C can thereby increase the surface area involved in thefusion and/or stabilization by 3-fold to 4-fold, depending upon thejoint involved.

The implant structures 20C can obviate the need for autologous grafts,bone graft material, additional pedicle screws and/or rods, hollowmodular anchorage screws, cannulated compression screws, cages, orfixation screws. Still, in the physician's discretion, bone graftmaterial and other fixation instrumentation can be used in combinationwith the implant structures 20C.

The implant structures 20C make possible surgical techniques that areless invasive than traditional open surgery with no extensive softtissue stripping and no disc removal. The assemblies make possiblestraightforward surgical approaches that complement the minimallyinvasive surgical techniques. The profile and design of the implantstructures 20C minimize rotation and micro-motion. Rigid implantstructures 20C made from titanium provide immediate post-op fusionstability. A bony in-growth region 24C comprising a porous plasma spraycoating with irregular surface supports stable bone fixation/fusion. Theimplant structures 20C and surgical approaches make possible theplacement of larger fusion surface areas designed to maximizepost-surgical weight bearing capacity and provide a biomechanicallyrigorous implant designed specifically to stabilize the heavily loadedlumbar spine.

Long Implant for Sacroiliac Joint Fusion

Elongated, stem-like implant structures 20D like that shown in FIG. 81make possible the fixation of the SI-Joint (shown in anterior andposterior views, respectively, in FIGS. 83 and 84 ) in a minimallyinvasive manner. These implant structures 20D can be effectivelyimplanted through the use a lateral surgical approach. The procedure isdesirably aided by conventional lateral, inlet, and outlet visualizationtechniques, e.g., using X-ray image intensifiers such as a C-arms orfluoroscopes to produce a live image feed, which is displayed on a TVscreen.

In one embodiment of a lateral approach (see FIGS. 85, 86, and 87A/B),one or more implant structures 20D are introduced laterally through theilium, the SI-Joint, and into the sacrum. This path and resultingplacement of the implant structures 20D are best shown in FIGS. 86 and87A/B. In the illustrated embodiment, three implant structures 20D areplaced in this manner. Also in the illustrated embodiment, the implantstructures 20D are rectilinear in cross section and triangular in thiscase, but it should be appreciated that implant structures 20D of otherrectilinear cross sections can be used.

Before undertaking a lateral implantation procedure, the physicianidentifies the SI-Joint segments that are to be fixated or fused(arthrodesed) using, e.g., the Fortin finger test, thigh thrust, FABER,Gaenslen's, compression, distraction, and diagnostic SI joint injection.

Aided by lateral, inlet, and outlet C-arm views, and with the patientlying in a prone position, the physician aligns the greater sciaticnotches and then the alae (using lateral visualization) to provide atrue lateral position. A 3 cm incision is made starting aligned with theposterior cortex of the sacral canal, followed by blunt tissueseparation to the ilium. From the lateral view, the guide pin 38D (withsleeve (not shown)) (e.g., a Steinmann Pin) is started resting on theilium at a position inferior to the sacrum end plate and just anteriorto the sacral canal. In the outlet view, the guide pin 38D should beparallel to the sacrum end plate at a shallow angle anterior (e.g., 15degree to 20 degree off the floor, as FIG. 87A shows). In a lateralview, the guide pin 38D should be posterior to the sacrum anterior wall.In the outlet view, the guide pin 38D should be superior to the firstsacral foramen and lateral of mid-line. This corresponds generally tothe sequence shown diagrammatically in FIGS. 82A and 82B. A soft tissueprotector (not shown) is desirably slipped over the guide pin 38D andfirmly against the ilium before removing the guide pin sleeve (notshown).

Over the guide pin 38D (and through the soft tissue protector), thepilot bore 42D is drilled in the manner previously described, as isdiagrammatically shown in FIG. 82C. The pilot bore 42D extends throughthe ilium, through the SI-Joint, and into the sacrum. The drill bit 40Dis removed.

The shaped broach 44D is tapped into the pilot bore 42D over the guidepin 38D (and through the soft tissue protector) to create a broachedbore 48D with the desired profile for the implant structure 20D, which,in the illustrated embodiment, is triangular. This generally correspondsto the sequence shown diagrammatically in FIG. 82D. The triangularprofile of the broached bore 48D is also shown in FIG. 85 .

FIGS. 82E and 82F illustrate an embodiment of the assembly of a softtissue protector or dilator or delivery sleeve 200D with a drill sleeve202D, a guide pin sleeve 204D and a handle 206D. In some embodiments,the drill sleeve 202D and guide pin sleeve 204D can be inserted withinthe soft tissue protector 200D to form a soft tissue protector assembly210D that can slide over the guide pin 208D until bony contact isachieved. The soft tissue protector 200D can be any one of the softtissue protectors or dilators or delivery sleeves disclosed herein. Insome embodiments, an expandable dilator or delivery sleeve 200D asdisclosed herein can be used in place of a conventional soft tissuedilator. In the case of the expandable dilator, in some embodiments, theexpandable dilator can be slid over the guide pin and then expandedbefore the drill sleeve 202D and/or guide pin sleeve 204D are insertedwithin the expandable dilator. In other embodiments, insertion of thedrill sleeve 202D and/or guide pin sleeve 204D within the expandabledilator can be used to expand the expandable dilator.

In some embodiments, a dilator can be used to open a channel though thetissue prior to sliding the soft tissue protector assembly 210D over theguide pin. The dilator(s) can be placed over the guide pin, using forexample a plurality of sequentially larger dilators or using anexpandable dilator. After the channel has been formed through thetissue, the dilator(s) can be removed and the soft tissue protectorassembly can be slid over the guide pin. In some embodiments, theexpandable dilator can serve as a soft tissue protector after beingexpanded. For example, after expansion the drill sleeve and guide pinsleeve can be inserted into the expandable dilator.

As shown in FIGS. 85 and 86 , a triangular implant structure 20D can benow tapped through the soft tissue protector over the guide pin 38Dthrough the ilium, across the SI-Joint, and into the sacrum, until theproximal end of the implant structure 20D is flush against the lateralwall of the ilium (see also FIGS. 87A and 87B). The guide pin 38D andsoft tissue protector are withdrawn, leaving the implant structure 20Dresiding in the broached passageway, flush with the lateral wall of theilium (see FIGS. 87A and 87B). In the illustrated embodiment, twoadditional implant structures 20D are implanted in this manner, as FIG.86 best shows. In other embodiments, the proximal ends of the implantstructures 20D are left proud of the lateral wall of the ilium, suchthat they extend 1, 2, 3 or 4 mm outside of the ilium. This ensures thatthe implants 20D engage the hard cortical portion of the ilium ratherthan just the softer cancellous portion, through which they mightmigrate if there was no structural support from hard cortical bone. Thehard cortical bone can also bear the loads or forces typically exertedon the bone by the implant 20D.

The implant structures 20D are sized according to the local anatomy. Forthe SI-Joint, representative implant structures 20D can range in size,depending upon the local anatomy, from about 35 mm to about 60 mm inlength, and about a 7 mm inscribed diameter (i.e. a triangle having aheight of about 10.5 mm and a base of about 12 mm). The morphology ofthe local structures can be generally understood by medicalprofessionals using textbooks of human skeletal anatomy along with theirknowledge of the site and its disease or injury. The physician is alsoable to ascertain the dimensions of the implant structure 20D based uponprior analysis of the morphology of the targeted bone using, forexample, plain film x-ray, fluoroscopic x-ray, or MRI or CT scanning.

Using a lateral approach, one or more implant structures 20D can beindividually inserted in a minimally invasive fashion across theSI-Joint, as has been described. Conventional tissue access tools,obturators, cannulas, and/or drills can be used for this purpose.Alternatively, the novel tissue access tools described above and in U.S.Provisional Patent Application No. 61/609,043, titled “TISSUE DILATORAND PROTECTER” and filed Mar. 9, 2012, which is hereby incorporated byreference in its entirety, can also be used. No joint preparation,removal of cartilage, or scraping are required before formation of theinsertion path or insertion of the implant structures 20D, so aminimally invasive insertion path sized approximately at or about themaximum outer diameter of the implant structures 20D can be formed.

The implant structures 20D can obviate the need for autologous bonegraft material, additional pedicle screws and/or rods, hollow modularanchorage screws, cannulated compression screws, threaded cages withinthe joint, or fracture fixation screws. Still, in the physician'sdiscretion, bone graft material and other fixation instrumentation canbe used in combination with the implant structures 20D.

In a representative procedure, one to six, or perhaps up to eight,implant structures 20D can be used, depending on the size of the patientand the size of the implant structures 20D. After installation, thepatient would be advised to prevent or reduce loading of the SI-Jointwhile fusion occurs. This could be about a six to twelve week period ormore, depending on the health of the patient and his or her adherence topost-op protocol.

The implant structures 20D make possible surgical techniques that areless invasive than traditional open surgery with no extensive softtissue stripping. The lateral approach to the SI-Joint provides astraightforward surgical approach that complements the minimallyinvasive surgical techniques. The profile and design of the implantstructures 20D minimize or reduce rotation and micromotion. Rigidimplant structures 20D made from titanium provide immediate post-op SIJoint stability. A bony in-growth region 24D comprising a porous plasmaspray coating with irregular surface supports stable bonefixation/fusion. The implant structures 20D and surgical approaches makepossible the placement of larger fusion surface areas designed tomaximize post-surgical weight bearing capacity and provide abiomechanically rigorous implant designed specifically to stabilize theheavily loaded SI-Joint.

To improve the stability and weight bearing capacity of the implant, theimplant can be inserted across three or more cortical walls. Forexample, after insertion the implant can traverse two cortical walls ofthe ilium and at least one cortical wall of the sacrum. The corticalbone is much denser and stronger than cancellous bone and can betterwithstand the large stresses found in the SI-Joint. By crossing three ormore cortical walls, the implant can spread the load across more loadbearing structures, thereby reducing the amount of load borne by eachstructure. In addition, movement of the implant within the bone afterimplantation is reduced by providing structural support in threelocations around the implant versus two locations.

Long Implant

FIGS. 88A-88C illustrate an embodiment of a long implant 800D forSI-Joint fusion or fixation that has been implanted through bothSI-Joints of the patient. The length of the long implant 800D can beselected to enter one side of the first ilium, cross the first SI-Joint,traverse the sacrum, cross the second SI-Joint, and exit the secondilium. In some embodiments, the length of the long implant 800D canadditionally include extra length to leave a predetermined length ofimplant proud of both surfaces of the ilium. For example, the longimplant 800D can have a length such that the implant is proud of eachsurface of the ilium by between about 1 to 10 mm, or between about 2 to8 mm, or about 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 mm, or less than about 1,2, 3, 4, 5, 6, 7, 8, 9 or 10 mm. In some embodiments, the long implant800D can be generally between about 100 mm to about 300 mm, or about 150mm to about 250 mm.

Besides the length, the long implant 800D can share many of the samefeatures as described above for the regular sized implant. For example,the transverse cross-sectional profile of the long implant 800D can berectilinear, such as triangular or rectangular. The long implant 800Dcan be made of a metal or metal alloy, such as titanium. In someembodiments, the surface of the long implant 800D can be roughenedand/or provided with a texture that promotes bone tissue ingrowth andintegration. For example, a porous and/or irregular surface texture canbe provided by titanium plasma spray coating the surface of the longimplant. The long implant 800D can also have a lumen for receiving aguidewire, and one or both ends of the lumen can have internal screwthreads. In some embodiments, the distal end of the long implant can beslightly tapered to facilitate insertion into a bone cavity and toprovide a visual identification of the distal end of the implant.

In some embodiments, as illustrated in FIGS. 88A-88C, the long implant800D can be implanted through the first ilium (not shown) and acrossfirst SI-Joint, through the sacrum and above the S1 foramen, across thesecond SI-Joint, and through the second ilium (not shown). In someembodiments, the long implant 800D can be implanted between the S1 andS2 vertebrae.

As shown in FIGS. 89A and 89B, to implant the long implant 800D, a guidepin 900D can be inserted, by for example drilling, through the firstilium and across first SI-Joint, through the sacrum and above the S1foramen and/or between the S1 and S2 vertebrae, across the secondSI-Joint, and through the second ilium. An incision can be made throughthe skin and tissue to the ilium to facilitate passage of the guide pin900D. Since the length of the guide pin 900D is known, the operator canmeasure the lengths of the guide pin 900D extending from both sides ofthe ilium and determine the length of guide pin 900D residing withinbone by subtracting the length outside the body from the total length ofthe guide pin 900D. Once the length of guide pin 900D within the bone isknown, the size of the long implant 900D that should be used can beselected by taking that length and adding the length of implant that isdesired to be left proud from each surface of the bone. In someembodiments, the length of the implant 800D to be used can be estimatedbefore surgery by imaging the pelvis region of the patient including thesacrum and the ilium. For example, an X-ray or CAT scan can be taken ofthe pelvis region, allowing the distance between the ilium surfaces tobe determined.

After the guide pin 900D is inserted, a cavity 902D can be formedthrough the ilium and SI-Joint and into the sacrum on both sides toreceive the implant. The cavity can be formed as described above bydrilling a bore and then shaping the bore using a broach. In someembodiments, the cavity can have a rectilinear transverse cross-section.As shown in FIG. 89C, the two cavities 902D should be aligned togetherso that the long implant 900D can be inserted through both cavities902D. In one embodiment, the guide pin 900D can have alignment featuresat both the distal end and the proximal end to facilitate alignment ofthe instrumentation such as the dilators and/or broach used to form thecavity. For example, as illustrated in FIGS. 90A and 90B, the alignmentfeature 904D can be a line, ridge, or slot that runs across the lengthof the guide pin 900D or at least runs across both ends of the guidepin. Alternatively, the alignment feature 904D can be a pin, such as atriangular pin or flat edge pin, that is located at each end of theguide pin. The broach 906D can have a complementary alignment feature908D along its guide pin lumen 910D, such as a slot or ridge, thatregisters the broach with the guide pin in the proper alignment. In someembodiments, once a first cavity has been formed, the second cavity canbe aligned with the first cavity using fluoroscopy. The first cavity isreadily visible under fluoroscopy and allows the operator to determineor confirm the proper orientation of the broach used to form the secondcavity.

After the cavities are formed, the long implant 900D can be insertedinto the first cavity and impacted through the sacrum and out the secondcavity. Some advantages of using a long implant 900D over separateshorter implants is that the long implant may provide enhancedstability, particularly in the sacrum. Use of the long implant may allowa more medial implant location relative to the implant location ofseparate implants, and generally the bone quality is better as theimplant location moves medially.

Variations and modifications of the devices and methods disclosed hereinwill be readily apparent to persons skilled in the art. As such, itshould be understood that the foregoing detailed description and theaccompanying illustrations, are made for purposes of clarity andunderstanding, and are not intended to limit the scope of the invention,which is defined by the claims appended hereto. Any feature described inany one embodiment described herein can be combined with any otherfeature of any of the other embodiment whether preferred or not.

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein are hereby incorporated by reference for allpurposes.

What is claimed is:
 1. A method of using a broach to create a cavity forreceiving a bone implant, the method comprising: inserting a broach intobone, the broach comprising a distal end that comprises a plurality ofcutting surfaces formed as teeth, each of which is disposed at an apexof the distal end and having a tip pointed distally to cut into bone,and an elongate body portion extending proximally from the distal end,the elongate body portion comprising a longitudinal axis, exactly threefaces, and exactly three apices each formed at the junction betweenadjacent faces; cutting into the bone with the cutting surfaces andforming a bore for an implant; removing the broach from the bone; andpositioning an implant within the bore.
 2. The method of claim 1,further comprising, at a time prior to the inserting step, inserting aguide pin into the bone.
 3. The method of claim 2, further comprising,at a time prior to the inserting step, drilling into the bone using theguide pin to create a bone channel, and wherein the inserting stepcomprises inserting the broach into the bone channel.
 4. The method ofclaim 1, wherein the inserting step comprising inserting the broachlaterally through an ilium, across an SI-joint, and into a sacrum.
 5. Amethod of using a broach to create a cavity for receiving a boneimplant, the method comprising: inserting a broach into bone, the broachcomprising a pyramid-shaped distal end, and an elongate body portionextending proximally from the pyramid-shaped distal end, the elongatebody portion comprising a longitudinal axis, exactly three faces andexactly three apices formed at the junctions between adjacent faces, thepyramid-shaped distal end comprising exactly three distal end faces thattaper in a distal direction, wherein each of the three distal end facesis an extension of one of the three faces of the elongate body portion,the pyramid-shaped distal end further comprising exactly three distalend apices, each of which is formed at a junction between adjacentdistal end faces, the pyramid-shaped distal end comprising a pluralityof cutting surfaces formed as teeth, each of which is disposed at one ofthe three distal end apices and having a tip pointed distally; cuttinginto the bone with the plurality of cutting surfaces and forming a borefor an implant; removing the broach from the bone; and positioning animplant within the bore.
 6. The method of claim 5, further comprising,at a time prior to the inserting step, inserting a guide pin into thebone.
 7. The method of claim 6, further comprising, at a time prior tothe inserting step, drilling into the bone using the guide pin to createa bone channel, and wherein the inserting step comprises inserting thebroach into the bone channel.
 8. The method of claim 5, wherein theinserting step comprising inserting the broach laterally through anilium, across an SI-joint, and into a sacrum.